In the same sense that different style machines use different types of needles, different style of sewing machines will use different types of bobbins.
Juki DDL-8700 Bobbin
The Juki DDL-8700 will use an L bobbin.
The L bobbin will also fit the other Juki DDL models, such as: DDL-8100e, DDL-8300, DDL-8500 and the DDL-5550N.
Juki DNU-1541S Bobbin
The Juki DNU-1541S uses an M bobbin.
The M bobbin can also be used on the Juki DU-1181N, THOR GC1541S, Seiko STH-8BLD-3 and the Consew 206RB-5.