完全都一样， 第一句更口语化吧。 其实我一般会说， 你有没有件衬衫

the difference is a bit like a and the.

有没有衬衫= do you have a/any shirt?

有没有一件衬衫= do you have the shirt?

in general, 有没有一件衬衫 doesn't make sense unless the dialogie is with context, or make it more specificly like 有没有一件黄色的衬衫? 有没有一件大点儿的衬衫?

Both are OK.

这两句根本就不一样。

They are correct both. But the former is more tend to oral.