IBO is International Bowhunters Organization

AMO is Archery Manufacturers Association and I believe it has now been changed to Archery Trade Association (ATA).

In terms of arrow speed it is usually considered as a test standard with specific criteria.....in other words...

IBO speed means a 70 lb draw weight, 30 inch draw length and a 350 grain arrow. AMO speed means a 60 lb draw weight, 30 inch draw length and a 540 grain arrow.

The AMO method has strict criteria that you need to follow where the IBO is a bit more liberal...