I'm Spanish and we have the word
gaviota to describe the marine bird. Searching for the translation I have found that can be translated as
seagull. Is there any difference in the meaning between both?
Not in this context, no.
"Gull" can be used as a verb, where it means to trick someone. But the nouns are synonyms.
My dictionary tells me that seagull is "a popular name for a gull".
Some distant knowledge tells me that the proper term is gull, but I practically exclusively use "seagull" to refer to this bird (and any that look remotely similar)