One general difference between 2-stroke and 4-stroke glow engines is valve maintenence. After break-in, and then after every five hours or so of runtime, You will need to check and/or adjust the valves on your 4-stroke engine. If the valves aren't adjusted properly, the motor will lose power and could possibly prevent it from running at all. It's not a big deal, and most 4-strokes come with the required "feeler guages" and tools required to do this.

If you are going to use a plastic spinner on a 4-stroke (rather than a locking prop nut, e.g.), make sure you use one with an aluminum backplate rather than an all-plastic one. The added torque that 4-strokes generate can break an all-plastic spinner into tiny pieces and then throw them all over the place at high speed.

4-stroke engines tend to be a bit more sensitive to nitro levels and will respond better to higher nitro content than 2-strokes. Most 2-strokes won't behave differently if you use 10% versus 15% nitro fuel, but most 4-strokes will provide more power with 15% than 10%. Ironically, many higher-compression 2-strokes will run better with 5% nitro than 15% nitro, but novice pilots buy 15% fuel anyway thinking that "more is better."

Lastly, most engine manufacturers recommend a "4-stroke" glow-plug rather than a "regular" glow plug.