Serious? I'll answer you with a question: Is there even any serious difference between Slovenian, Croatian and Serbian language?

??? I am just asking how different are these language. If i would know how different they are i wouldnt ask.

And I answered (more or less). Moravian stands between Czech and Slovak. Of course, there are differences – in grammar, vocabulary, accent, in everything. If there was no Czecho-Slovakia, I guess Czechs and Slovaks would understand each other just like Slovaks and Poles do. That means – not so well as nowadays. However, once I met a Czech guy who did not understand me and needed to concentrate to that what I was telling him. He spoke standard Czech and I spoke standard Slovak. It's well-known that Czech youth and children have problems with understanding Slovak (a Czech young model was confused in Bratislava and asked for a slower communication because she did not understand Slovak well). Slovak children still watch movies in Czech unlike Czech children who don't watch movies in Slovak. If there is a Slovak movie in Czech rep., it has Czech subtitles. Slovak is softer than Czech. Nevertheless, it's not that bad yet.. :P

Maybe not proper examples, but here's a Czech accent from Prague :

Debilní Kecy Pražáků

and Slovak accent of blondes :

Blondínky otvárajú víno-také milé….wmv