Question

how does a dissolve differ from a fade?

a dissolve is a transitional cut, whereas a fade is not.

a dissolves transition occurs simultaneously on the screen, whereas a black screen separates the two parts of a fade.

a dissolve can be used to mark a connection between two shots, whereas a fade cannot.

a dissolve emphasizes the image, whereas a fade does not.

a dissolve can be used to mark the passing of time, whereas a fade cannot.

Explanation:

A dissolve overlaps two shots simultaneously on screen, while a fade transitions to/from a black screen that separates the start/end of the shot sequence. Other options are incorrect: both are transitional cuts; both can mark connections or time passage; neither inherently emphasizes an image more than the other.

Answer:

A dissolve's transition occurs simultaneously on the screen, whereas a black screen separates the two parts of a fade.