IP-editing is related to AccountlessUserIdentification. The relation is, that AccountlessUserIdentification relies on and required IP-editing, and a system that supports accounts may also support IP-editing. WikiPedia supports both for the most part of it whereas WardsWiki's EditMode? is IpEditingOnly.
IP-editing got it's name from the fact, that in any case the system to be edited knows the IP of the editor and in absence of a login to an account, regardless of accounts being supported on that system or not, treats the IP-number like the name of an account. On systems which support accounts and IP-editing and record the account name together with the edit, the IP will be recorded instead.
Just like accounts can be blocked or deleted, a system can support the blocking of any IP or RangeBlock? a number of IPs in order to defend against spamming and other forms of vandalism.