Can VEX EDR use parts from VEX IQ ?

VEX EDR is the steel and aluminum robot-building platform, and VEX IQ is the mostly-plastic platform. Since both are based on holes with 1/2" spacing, it is easy to build structures that contain parts from both systems.

If you are talking about the VEX Robotics Competition (VRC) which uses VEX EDR, than answer is no, you cannot. VEX IQ parts are not legal for the VRC.*

*Except where the VEX IQ parts are identical to VEX EDR parts, like steel axle shafts.

Only those that are in both product catalogs - rubber bands, soft shaft collars, pre-cut shafts in IQ (no cutting in IQ).

Everything else is different (and cheaper and smaller and motors run slower) in IQ

Rule R5 C:

Unless identical or used purely for decoration purposes.

Thanks all great help

There is an exception, too. You can use the pegs from VEX IQ for the sole purpose of attaching the license plates.