Interference Manager vs Clash Detection (Which one?)

What is the difference between "Interference Manager" and "Clash Detection"?   We have Interference Manager, but it appears the interface is much easier with the Clash Detection?  Are they different tools and it appears they require seperate licenses?  Will Interference Manager be replaced with Clash Dection in an upcoming release in Bentley Architecture?

Can anyone shed some light on this?
Thanks

Brian Thomas

Selser Schaefer Architects