Difference - burp cloths and muslin cloths!?

Muslin squares are thinner, burp cloths are thicker, kinda fleecy , and bigger

I think it's mainly just the shape and thickness that differs between the two. You don't necessarily need burp cloths as well as muslin squares - the squares will do the job of both, and in my experience it's good to have a lot as you do go through them. A decent size muslin cloth can be used as a swaddle, a cover, for mopping up milk/spit, and folded over can be thrown onto your shoulder for burping or tucked under babies chin as a bib for feeding. A burp cloth is usually a smaller rectangular shape for draping over your shoulder or in front of baby while burping - they are usually made of muslin also but have a few layers to make them a bit thicker / more absorbant - but the size and shape means you can't really use them for much else. X

It's all the same!