The older model Yongnuo 602 units comprised a pair of different units, one solely a transmitter and the other a receiver. The newer 603 incorporates both functions into one unit. You still need at least two of them to operate a camera or flash but the devices are identical. A further advantage is that they all use AAA batteries, whereas the 602 transmitter requires a CR2 - not expensive or difficult to source, but going all AAAs is obviously more convenient.
One other issue is ensuring you purchase the correct connector for your camera, if you wish to use the triggers as a remote shutter release. For example, there are two types of remote/cable release socket on Canon DSLRs, one fitted to entry-level cameras and another on the higher-end models. I use both.
Just for a little more clarity (I hope), strictly speaking a "transceiver" is a device in which the transmitter and receiver circuits share some components. This may be true of the 603 or it may be that it is simply a case containing two distinct circuits, although they share a power supply. It doesn't matter for your purposes anyway.
Short answer is, if you want inexpensive, reliable, "dumb" triggers (not ones that can also alter flash settings) buy as many Yongnuo 603 units as devices you want to trigger plus one to set them off, and ensure you obtain the correct lead if you want to remote trigger your camera.