The ratcheting crimpers more expensive because they bend the metal clamping tangs in a heart shape around the wire strands, curling the skinny edges back into the wire. This gives a much better clamp on the wire than simply folding the broad flats down on the wire strands, which is what you get using needle nose pliers or the simpler crimp tools. The tool also similarly crimps the insulation/strain adjust tangs in a similar fashion at the same time. They also have a ratcheting mechanism and small spring clamp for holding the pin/socket housing while you fit the wire to it.

I'd equate the difference to using a can of spray paint versus a pro air gun to paint a car. Both get color on the car, but one does it much more smoothly and consistently.

-Zeke