We need to consider that Catalan and Spanish (as French, Portuguese or Italian), come from Latin, so they have the same grammar and mostly the same roots for the words. However, of course, they are two different languages, and we didn't focuse on different vocabulary, it's just that "mesa" is in Spanish and "taula" in Catalan, we can't do anything, they are just different words.

We didn't think yet about the Catalan cours to englishspeakers, so I can't answer you.

I think it's important that you have not only Spanish in mind, but also French, when learning Catalan vocabulary. Just like in the example asfarer gave, "mesa" in Spanish is "taula" in Catalan, which is closer to "table" in French. Same for "llet" which I find is closer to "lait" than to "leche", for example.

You should also understand that Catalan has a strong Occitan influence because of its geographical position.

According to the dialect continuum, Catalan is the language that links Spanish to Occitan as you can see in the image below.

I also do the Catalan in Spanish, learning two languages at the same time. For me Catalan seems to be (or it reminds me) sometimes closer to Italian, see: formatge - formaggio (Sp. queso) or sento - sento (Sp. oigo), of course these are only just examples. Sometimes the sentence is the same as in Spanish, word-by-word... But of course I am in the very beginning.

Gràcies per les respostes! I can definitely see the resemblances to French and Italian. The most striking feature to me is the extent to which Catalan prefers to end words with consonants rather than nouns - something that makes it sound quite different from Spanish and Italian. And some of the vocabulary, like "gos" for dog seems to be unique.