The main difference
A traditional video intercom lets you speak and open from the indoor monitor. An IP system can add mobile calls, remote management, better image quality, access control integration and more expansion options.
When an IP system is useful
It is especially useful in communities, homes with separate entrances, small businesses, second residences and spaces where it is useful to answer even when nobody is inside.
What to check before deciding
Existing cabling, number of homes or users, distance to the door, power, network connection and real needs must be checked. Sometimes part of the installation can be reused, and other times it is better to renew it to avoid future problems.