There are teeth on the bottom of snowshoes called crampons that provide traction. You need different levels of traction based on the terrain you’re crossing.
If you plan to snowshoe mostly on packed snow that may include icy areas, or you want to have good control when ascending or descending hills, you’ll want shoes with larger crampons to give you good grip. For snowshoeing in powdery, fresh snow or on gentle, flat trails, you will be fine with smaller crampons. However, since extra traction won’t ever have a negative effect on your experiences, you’re always better to choose too much traction rather than too little.