what is the main difference between an ids and an ips?
IDS vs. IPS. While many in the security industry believe IPS is the way of the future and that IPS will take over IDS, it is somewhat of an apples and oranges comparison. The two solutions are different in that one is a passive detection monitoring system and the other is an active prevention system.
The terms aren't precisely defiend in standards; but in general usage, here is a breakdown: IPS-Intrusion Prevention System-inspects traffic flowing through a network and is capable of blocking or otherwise remediating flows that it determines are malicious. Usually uses a combination of traffic and file signatures and heuristic analysis of flows. IDS-Intrusion Detection System-similar to IPS but does not affect flows in any way-only logs or alerts on malicious traffic. Firewall-prevents or allows traffic between interfaces based on configured rules.