The major difference is that wood shapers and routers use different types of cutters. Actually, routers win here as the range of router bits includes over 30 different profiles. Routers are also much smaller, which makes it easier to transport them and lets you work on more delicate work pieces. In addition, a smaller cutter diameter enables greater RPM, which results in cleaner cuts. Shapers are good for processing large batches of work with a relatively low vibration level and rarer cooling pauses. It's an excellent tool for heavier shaping works.