ولكن is used after listening or mentioning some facts and partly accepting then making a comment on them... whereas لكن is used for contracting..

As Cherry said, و means "and". So if you want to conjugate longer sentences, it's better to use ولكن. Also, notice that we don't leave a space after و when we type in Arabic.

نفس الشيء

There has to be a context to decide for the better way to say it . Both really are interchangeably used. و means 'and' , which has no adequate translation into English , literally means ' and but ' . هو ظريف و لكن لا يعجبني هو ظريف ، لكن لا يعجبني I think it is all the same ! Just another way to say it !