¿Cuál es la diferencia entre un búho y una lechuza?
Are they just different words for an owl? Or are they different kinds of owls? The Wikipedia isn't too clear.
Regarding the difference between the two, (if there is a distinction to be made), I believe that Eddy is correct that owls with tufts of feathers which stick up over their heads (sometimes referred to as "horns" or "ears") are sometimes designated as "búhos." Here is a Wikipedia exerpt:
Lechuza es el nombre común de varias aves del orden de las estrigiformes. Habitualmente designa especies que, a diferencia de los búhos, no tienen plumas alzadas que parecen orejas.
The RAE also makes reference to the fact that the word "búho" refers to owls of the horned variety:
Buho • Ave rapaz nocturna • indígena de España • de unos 40 cm de altura • de color mezclado de rojo y negro, calzada de plumas • con el pico corvo • los ojos grandes y colocados en la parte anterior de la cabeza, sobre la cual tiene unas plumas alzadas que figuran orejas.
When you look at the definition of "Lechuza" in the RAE, it seems to be a description of the common barn owl, Tyto alba, or in Spanish, "Lechuza común," a type of owl which consequently is of the un-horned variety.
I think that the use of the word "búho" for certain types of owls is probably related to the fact that the word stems from the Latin word "bubo." Coincidentally, the animal of the genus and species Bubo bubo is "Búho Real" (in Spanish).
With some owl species, the distinction is not alway immediately apparent. For example, the Short-eared owl (Asio flammeus) has "ear tufts" which are not immediately apparent and this is reflected in the fact that it is commonly referred to as both "búho campestre" and "lechuza campestre."
Even more confusing, in certain countries (México, El Salvador, Guatemala and Honduras), horned-owls (búhos) are sometimes referred to as tecolotes. In addition there are several other common names given to various types of owls such as mochuelos, autillos, cárabos, nuco and caburés.
All that being said, I think that in Spanish any distinction that might exist between the terms "lechuza" and "búho" is often lost in everyday speech (as already alluded to by Gekkosan), just as in English many people will only make reference to "owls" rather than drawing a distinction between horned-owls and barn-owls. This is probably due to the fact that most people don't go around naming animals by their Linnaean classification. That is to say that most people are not particularly interested in taxonomic names.
In terms of Linnaean classification, however, the term "owl" is a word used to reference all animals of the order Strigiformes (las estrigiformes). This order is also further subdivided into two general families. The common term "lechuza" refers to the family Tytonidae (barn owls). The other family, Strigidae, includes animals which are variously referred to as búhos, lechuzas, mochuelos, tecolotes, autillos, cárabos, el ñacurutú and el chuncho, among others. Considering all this, I think that you can probably safely get away with using either "lechuza" or "búho" in order to refer to all owls without anyone looking at you strangely.
Strigidae (Búhos, lechuzas, mochuelos, tecolotes, autillos, cárabos, etc)
I did once see a reference for "búho" being a long eared owl, however, I can´t remember where. They are, however, two words meaning owl.
"Búho" is written with "B", and "Lechuza" is written with "L".
Sorry, just being obnoxious.
I use both words indistinctly. I have never hear of there being a universally-known distinction between the two words, if there is one at all.
This image appears in Google images under "Buho"
This image appears in Google images under "Lechuza"
I invite you to draw your own conclusions.
It seems to me that Búho is more the word for an owl, while lechuza has different possibilities to use it. I've been called a lechuza as a joke by my cuban friend because I was spending too much time on World of Warcraft. =p