The answer to 'difference between drip edge' is that drip edge and gutter apron are two different types of roof edge flashing used to protect the roof and exterior walls from water damage. Drip edge is a metal flashing installed along the roof's edge to direct water away from the fascia and into the gutters, while gutter apron is a flashing that extends from the roof's edge down into the gutter to prevent water from seeping behind the gutter.
The main differences are that drip edge is installed on the roof's edge, while gutter apron is installed inside the gutter. Drip edge helps prevent water damage to the fascia, while gutter apron helps prevent water from seeping behind the gutter. Drip edge is generally less expensive and easier to install, while gutter apron provides more comprehensive protection but may cost more and be more difficult to install.