Yes of course there are synonyms in all languages - but I specified "a lot more words". If you look at the link I included in my first reply under "vocabulary comparison" you'll see an example of what I mean. And thats just the biggest one - there are islands in Croatia where I (as a native speaker) might have better luck understanding Czech than the local variants.
Don't think that undermines my claim at all - they understand the words because they're familiar within the slavic language group in general (even though they might be derivations and used or spelled differently). Its like saying Italian/Spanish are the same because speakers might understand words between them. With the translation argument - you also of course have to ignore the fact that Serbia writes in cyrillic and Croatia in latin alphabet.
Don't think that undermines my claim at all - they understand the words because they're familiar within the slavic language group in general (even though they might be derivations and used or spelled differently). Its like saying Italian/Spanish are the same because speakers might understand words between them. With the translation argument - you also of course have to ignore the fact that Serbia writes in cyrillic and Croatia in latin alphabet.