I have both Pellia & Subwassertang. They are kept in separate aquariums. You really need to take them out of you tank and examine each one with a magnifying glass. Then you will see the difference.
I hope this comparison helps.
Scientific Name: Monosolenium tenerum
Pellia is a liverwort...
I have a very nice riccia mat (about 4"x11" plastic mat). It is quite full and nice now. The plastic mesh is black so it can bend nicely onto a substrate.
I would like to trade this for some plants that you might have:
Blyxa japonica or alternifolia