Either is used. It depends on what you have on your house
All ranges can use a 3 wire plug, a 4 wire plug, or hard wired.
Some ranges are "hard wired", which means there is no plug. The wire will come out of the wall and tie in directly on your range.
Some houses have a 3 wire plug, which means the plug will have only 3 slots on the outlet.
Some houses have a 4 wire plug, which means the plug will have 4 slots on the outlet.
Always look at your existing range and how it is connected to the house before buying a new plug.
The instructions will tell you how to connect each plug to the new range.