Propagation Delay is the time taken by the packet to travel through the channel. It is the time taken to travel through the link and reach the destination. For example, if my computer is connected to your comp and the transmission rate is the distance between the two computers divided by the speed at which the data travels through that link. If the distance between the two computers is 1000 m and the speed is 10 m/s then the transmission delay is 100 seconds.
Transport Delay is the same as propagation delay.
Transmission Delay is the time required to put the full packet on the link. It depends upon the size of the packet (L) and the link rate (R). The formula for calculating txn delay is L/R.
Round Trip Delay or Round Trip Time (RTT) is the time taken by the packet to travel from Comp 1 to Comp 2 and then coming back to Comp 1. This includes the processing time (which includes transmission delay at the Rx side) at the receiving end (at Comp 2).