That’s a good location for it, just consider if / when the Apex is approved for payments, presenting your arm to a terminal may be more difficult than a hand…
Quite a lot actually, the list of what is similar is shorter
Both:
High Frequency,NFC and ISO14443A
2x14mm
Otherwise, the chips and purposes are very different.
For your situation
No, I would recommend the NExT implant for your Hand and the Apex for your arm.