For native English speakers
I've seen lots of comments here on how hard Spanish is for native English speakers. Apparently and because of the questions and doubts I see, I would say you have problems with subjunctive, the difference between indefinite past and preterite and the direct and indirect objects. Maybe there are more things.
Now I'm going to ask the other-way-around question. What do you think are the most difficult things for Spanish speakers who learn English?
11 Answers
Great Question, Polenta 
From observation and my experience of learning to speak Spanish and helping native Spanish-speakers to improve their English, two of the most difficult aspects for native speakers are (include):
1.Phrasal verbs eg: go back = return = volver; get ready = prepararse, arreglarse Está preparando la cena =She is preparing the dinner.
2.Syntax ie: word order Spanish allows for a much greater flexibility in word order than English!
3.Prepositions: in/on/under/through etc...
4.Double negatives: These are permitted in Spanish, but not in English! We do not say/It is not good English to say: I don't know nothing!
eg: ¡No sé nada acerca del robo en el banco!. = I don't know anything about the bank robbery!
5.Verb usage/ translation: In Spanish you say Tengo hambre = Correct translation = I am hungry = literally: I have hunger A different verb is used which can cause problems for English and Spanish speakers at beginner level who are included to translate everything too literally...ie: word for word In English we say I am hungry but you use the verb to have hungry not, to be hungry!
For me it was the 244 irregular past participles. In Spanish there are only around 12 or so, like "visto" for "ver" "puesto" for "poner" "escrito" for "escribir" and a few others.
English past participles are sometime exactly the same as the simple past tense: I jumped vs. I have jumped.
Many English speakers will use "seen" instead of the past tense "saw." "I seen him last week." is very common.
I could provide a list of the 240+ irregular past participles, but it would take up too much space. I have them in one of my dictionaries, I assume they can also be found on a Google search. Hmmmmm. I just found them here they are.
Irregular English past participles
Two hard ones (I may think of more later, but these are ones I notice in Spanish speakers with good English):
Use of the subject placeholder “it”. “It” is necessary in places that it is not in Spanish, and if you forget to use “it”, it sounds bad.
In vs. on. When I am on a car I am on top, to be inside I am in it. But when I am on a train, normally I am inside. I can be in a train, but we don't normally say that. I watch things on television, not in it, and if I am watching the cat crawling around on top of the television, I have to use “top”.
I think English Modals are one main problem. They don't exist in Spanish.
Another one is phrasal verbs. English has very many of them.
And of course the many idioms. These vary between English speaking countries.
Polenta:
You've already received some good answers here. If you want learn about several other difficulties, just search google for - hardest things when learning English - There are are tons of good hits for this.
Some will address this from a Spanish speakers perspective and others will be more generic, but in most cases, the difficulties of learning English are not unique to Spanish speakers. I have taught Spanish speakers, Jordanians and Hmong and the difficulties are more similar than they are different.
Here is one very good link,
After decades of being in touch with English I have great respect for this language. It's very hard to even get to know English or any other foreign language as you know your own mother tongue. My dream would only be to communicate with a certain "dignity" and to be understood.
Having said that, there is a topic that I know all Spanish natives have a lot of problems with. At least around here although I guess it is all over.
P h r a s a l v e r b sssssssssssssssssssssss
It's like baving to learn another language. It's a huge problem. No native Spanish speaker that I know can manage this topic. It's a pain in the neck for all of us. Are you sure native English speakers know them well? LOL
Just think of the many meanings of "go off"
Adding to those suggestions made by Bosque and Nkm:
Spelling: Spanish is very, very, uniform in comparison to English, which often has multiple variations in spelling for words that sound the same, multiple pronunciations for words that are spelt the same, and some words that aren't even pronounced the same way they are spelt
Translation of "de": Often the "de" constructions in Spanish will be adjectival constructions in English, but not always. Eg. Pelota de tenis = Tennis Ball but Ovillo de lana = Ball of wool. Knowing when to use an "of" construction in English versus an adjectival construction may be difficult.
Pronunciation, regional differences between American/British English & lack of exposure to the language.
What are the hardest things about learning: English vs Spanish?
Pronunciation.
I recently coached a Spanish man who was going to go for a job interview here in England. He's an intelligent guy, knew his job thoroughly, had thought of almost every question they could ask him and had practised and rehearsed the answers.
The problem was that I could only understand about 1 word in every 6 that he said. Even spoken slowly and in context the words were not intelligible. The poor bloke had been learning English for almost ten years and would have passed an exam with few problems but he'd only ever studied in Spain.
He painstakingly rewrote ALL of his notes in "phonetics" and spent a week practising. The next time we met he had improved immensely. He phoned me a couple of week ago to tell me they'd given him the job so I was delighted for him.
By the way........ This seems to affect Spanish people more than American Spanish speakers in my experience. I have no idea why
Patch: I was just going to say the same.
Pronunciation!!!!!
For a Spanish native most sounds simply sound the same: hear, hair, her, ear, even head
I have a student from the south of Spain where you don't pronounce all letters anyway. so for her it is quite impossible to distinguish "similar" sounds.
And number two: Phrasals!!
Polenta:
This isn't answering your original question, but deals with one way to overcome many of the difficulties mentioned. I have used this program with great success with Mexican learners. It is Mango Languages, which is available free of charge from many libraries, at least in the U.S.
It deals with forced repetition of common phrases and vocabulary. Such things as omission of subject pronouns, wrong use of possessive pronouns, phrasal verb usage, talking about the weather, talking about time in the past (without hace/do/make), the prolific use of do/did/don't/didn't for negative statements and questions, and many other things can be readily addressed by frequent use of this program.
There are units available both English learners and Spanish learners (and many other languages.) There are basic conversation units and specialized units for business, the medical profession, lawyers, librarians, etc. It is available for computer and smart phones. There are hundreds of lessons available, each one might take 20-30 minutes to complete.
I have used the Spanish - English versions with students, and I have spent about 100 hours doing the English - Spanish versions, which is helping me to speak Spanish without having to pause to think of the next word.
