The difference between Combination and Fusion

Combination as a noun:

The act of combining, the state of being combined or the result of combining.

Combination as a noun:

An object formed by combining.

Combination as a noun:

A sequence of numbers or letters used to open a combination lock.

Combination as a noun (mathematics):

One or more elements selected from a set without regard to the order of selection.

Combination as a noun:

An association or alliance of people for some common purpose.

Combination as a noun (billiards):

A combination shot; a billiard; a shot where the cue ball hits a ball that strikes another ball on the table.

Combination as a noun:

A motorcycle and sidecar.

Combination as a noun:

A rapid sequence of punches or strikes in boxing or other combat sports.

Fusion as a noun (physics):

The act of merging separate elements, or the result thereof. A nuclear reaction in which nuclei combine to form more massive nuclei with the concomitant release of energy. A style of music that blends disparate genres; especially types of jazz. A style of cooking that combines ingredients and techniques from different countries or cultures The act of melting or liquefying something by heating it. The result of the hybridation of two genes which originally coded for separate proteins. The process by which two distinct lipid bilayers merge their hydrophobic core, resulting in one interconnected structure. The act of two characters merging into one, typically more powerful, being; or the merged being itself.

Fusion as a verb (nonstandard):

to combine; to fuse