Baby change tables come in different models. The biggest difference you will notice is that some have legs and some do not. Most baby change tables retract from a wall. Some, after retracting, also have folding legs that you can release, while others rely on the strength of their hinges to keep the table secure.
Both types of baby change tables, those with legs and those without, are tested and safe for your baby. The makers of baby change tables are held under the highest scrutiny for the quality of their products. Design differences such as legs play little part in anything except unique design for a specific company.
If you are hesitant to use a baby change table that doesn't have legs on it, you shouldn't worry. The table wouldn't be in the room if it wasn't verified as perfectly safe and structurally sound for use with your child.