Russian and Ukraine language difference big?

not too much, it's like almost same, but have different words, but same prononse.

And ukranian or russian man, can understand main point of any speaking on any language.

if you choose between learning russian or ukrainian - learn russian, definitely.

Hey
Russian and Ukraining languages are in the same family, it is a bit like Portugese and Spanish, speakers of both can understand each other, but written words can be very different and for foreign speakers  Generally, Russian is more widely spoken. Practically everyone in Ukraine can speak standard Russian or with accent.  And about hald of population in Ukraine can only speak Russian.  But Ukrainian language can be very interesting from linguistic point of view.  It is older than modern Russian. It also has additional vocabulary borrowed from surrounding countries such as Poland, Hungary, Romania. 

It is easier to learn Russian simply because there is more literature and tutorials for Russian.  
I found this site recently, they even teach you how to date someone in Russian :-)  http://voices.plus.googlepages.com/