QUICK ANSWER
"I think" is a form of "I think", a phrase which is often translated as "pienso". "Yes" is an interjection which is often translated as "sí". Learn more about the difference between "I think" and "yes" below.
I think(
ay
thihngk
)A phrase is a group of words commonly used together (e.g., once upon a time).
yes(
yehs
)An adverb is a word that describes a verb, an adjective, or other adverbs (e.g., to run quickly, very tired).
An interjection is a short utterance that expresses emotion, hesitation, or protest (e.g., Wow!).
A noun is a word referring to a person, animal, place, thing, feeling, or idea (e.g., man, dog, house).
