A French drain collects water. It's a trench lined with filter fabric, filled with washed gravel, and fitted with perforated pipe. Water in the soil finds its way into the pipe and flows downhill to an outlet. Outside, French drains catch water before it reaches the foundation. Inside the crawlspace, a perimeter drain catches water seeping through the walls.
A sump pump moves water. It sits in a pit at the lowest point of the crawlspace, and when water fills the pit, the pump switches on and pushes it out through a discharge line well away from the house.
If your lot slopes enough to drain water naturally, an exterior French drain may be all you need. If the crawlspace is lower than the surrounding ground, water has nowhere to flow, and a sump pump is needed to lift it out.
Many Triangle homes need both: an interior drain that collects water along the walls and carries it to a sump pump. Once the water is managed, encapsulation and a dehumidifier keep the space dry.
The right answer depends on your house and lot. We inspect where the water is coming from and recommend only what's needed, in writing.