That would have a different meaning. On the surface it may seem similar, but one is telling vs. a lone thought. There was a similar issue on another question where someone was trying to use "paroli" and "diri" interchangeably, which respectively mean "to speak" and "to say." While on the surface they seem the same, in each instance something different is being expressed. I am not articulate enough to explain more clearly, nor do I want to presume entire authority on the subject, but I hope that helps.
In this case they both mean the same thing. In the sentence "There is a woman in the cafe", "there is" is a dummy subject. In English all clauses which are not imperatives need a subject, so we sometimes add a subject which doesn't mean anything just to make the sentence follow our grammar rules. "There is a good idea". Where is the good idea? It isn't anywhere. We just mean "The idea is good". "It is snowing". What is snowing? We just mean snow is happening.
Esperanto dispenses with these dummy subjects. "Estas bona ideo" - the idea is good/there is a good idea. "Neĝas" - snow is happening/it is snowing. "En la kafejo estas virino" - a woman is in the café/in the café there is a woman.
I know that in theory, any root can take any part of speech, although in practice that's limited to what makes sense. If I understand things right, "kafeja" would be less something that's like a cafe and more something relevant or pertinent to cafes.
Like in English, nouns can be used as adjectives such as "employee discount" or "towel rack". I think "kafeja antaŭtuko" would be a "cafe apron", an apron worn in cafes.
The suffix -ulo means "someone with the characteristics of the root", like "junulo" means "one who is young", or "young person" and "proksimulo" means "one who is near", or "neighbor". It does seem to specify a person or at least a living creature, and in fact as a stand-alone root, "ulo" means "guy" or "dude" (although it's gender-neutral).
If it weren't for that stipulation, I would suggest "kafejulo" or "kafejula", but I don't think that would work. You may just have to say "tiel kafejo", "like a cafe".