EXPIRE_TIME is for a connection that has been established, and the database wants to know if that connection is still valid, ie, the client that established it is still present and capable of making requests to the database. When set, the database occasionally contacts the client over the network to ensure that it is still responding.

INBOUND_CONNECT_TIMEOUT is a connection parameter. When a client initiates a connection request, if something goes wrong during the connection to-and-fro between client and server, the INBOUND_CONNECT_TIMEOUT decides when we will abandon the connection attempt.