The most notable difference is that the 1991 engine uses a distributor, while the 1992 engine uses coil-on-plug ignition. This means that the 1991 engine will require a distributor and ignition wires, while the 1992 engine will not. Additionally, the 1992 engine has a slightly different oil pan and oil filter location, so these parts may need to be swapped out as well.
Overall, the swap is relatively straightforward and can be accomplished with basic hand tools. However, it is important to be aware of the minor differences between the two engines to ensure a successful installation.