Protector vs. mattress pad vs. topper
The main difference comes down to purpose. A mattress protector focuses on protecting the mattress. A pad or topper is intended to provide additional cushioning.
How a protector fits
Many mattress protectors fit much like a fitted sheet, using deep pockets or an elastic skirt to help the protector remain in place over the mattress.
What protectors are made of
Construction varies by product. Common designs may use cotton or polyester surfaces combined with a breathable, moisture-resistant layer. Materials and construction can affect both feel and airflow.