BOV is on Intake
side. It has nothing to do with exhaust.
It vents out the air to prevent compressor surge due to the
throttle is slammed shut when you shift.
Bypass valve works the same way as BOV. The only different is
it recirculates the air back into the Intake
(before the compressor wheel)
Bypass valve is common to car that come with AFM or MAF
(non-MAP type or non-speed density air measuring system)
This is to prevent venting metered air out.
If the metered air is vented out too much, the car will run too rich
and may stall.
On the other hand, wastegate lets the "exhaust" bypasses the turbine wheel.
The main purpose of the wastegate is "to limit boost"
So, the wastegate is more like boost controller than the BOV or BPV.
By the way, BOV, bypass valve and wastegate will not work on N/A car.