I think miniature quilts are also known for the block size. Rather than a single 12" x 12" block used for a miniature, several smaller blocks would be used. One I own has 9-patch units that measure 2 3/8" square. The miniatures at the International Quilt Study Museum are tiny - I do not know how people can work with such small pieces. I do not remember any of them having pieces larger than 1/2". Most of those quilts are less than 12" square.
Doll quilts are entirely different, from what I have seen here. They are an art form that allows for a great range of interpretation and expression.
Chele is an expert on doll quilts. You could PM her to ask for more information.