Actually, the 101 and 102 designate slightly different tool holders. The U shaped slot has a flat bottom on the 101. The bottom of the slot has a lengthwise v-notch in the 102, to help hold boring bars and other round tool bits.
The numbering system is pretty universal amongst all the Chinese tool holders I've ever come across. By the way, 104 is a holder for large round boring bars, 107 for parting blades, 110 is a knurl. and 116 is a double-ended 60º carbide insert tool (I think for threading).