I might get killed for this, but oh well. Apart from the obvious (12/13 members of which several are non-Korean), I feel like WJSN and IZONE also have a somewhat similar vibe and musical style, and quite similar voice profiles. The main difference is probably that WJSN's niche is better defined ("cosmic", I'd probably call it dreamy) while IZONE keep things a little broader and a little more generic, trying to reach a wide audience. They are definitely close enough that I could easily imagine IZONE doing many of the WJSN songs and vice versa without it being a stark break from their own songs or image. Now, this is not to bash IZONE and I don't think they are bad. However, I feel like WJSN does everything IZONE does, just everything a little better. Their voices are similar but better, their music is somewhat similar but better and more interesting/innovative, their style is more unique as well while IZONE just go for a fairly generic kind of elegance. IZONE is a good group, but WJSN is a great group within the same category.