OSPFv3 Prefix Suppression

it should be equal, if you type “ipv6 router ospf 1” you are also creating ospfv3 process, just with old command, this does not support address families.
However if you type “router ospfv3 1” you can enable prefix suppression for both families, ipv4 and ipv6 at the same time.

router ospfv3 1

In case you want to enable prefix suppression just for ipv6 family you configure it under address-family configuration

router ospfv3 1
 address-family ipv6 unicast

Also configurations on interface is doing the same.

ipv6 ospf prefix-suppression
ospfv3 prefix-suppression      ! enabled for all precesses
ospfv3 1 prefix-suppression    ! enabled for process 1

Implicit interface configuration has priority over explicit configuration done under OSPF process.