body switch

When two characters swap bodies.

This means the characters' entire identities (including memories etc) have been transferred to the other's body (in contrast to personality switch, where only the personality is switched).

There should be some clear indication that the swapping has taken place in the picture or in the commentary, otherwise it's just a personality switch.

A good example is Danbooru post #4619026.

This tag implicates personality_switch (learn more).