Cordless trim router vs. cordless plunge router — which do I need?

For edge work, round-overs, chamfers, and flush-trimming, a compact fixed-base trim router is what most reviewers recommend. For mortising, inlay, and template work, you'll want a plunge base — several of these systems (DeWalt, Milwaukee, Makita, Bosch) sell a separate plunge base that fits the same motor.