So what is the difference between muslin and cotton fabric? Muslin is cotton and woven and bleached, sometimes.
Muslin has a different thread count and shrinks more than the fabric we use for quilts. However, if you prewash it in hot water and dry in a hot dryer a couple of times, you can use it in a quilt. I buy the muslin that claims it won't wrinkle -much less ironing required - LOL.