General synonyms:
* Assortment: A collection of different things
* Diversity: A range of different things
* Mixture: A combination of different things
* Range: A wide selection of things
* Selection: A choice of different things
* Spectrum: A wide range of things
* Spread: A wide distribution of things
* Collection: A group of different things
* Array: A large number of things arranged in a specific way
Synonyms emphasizing difference:
* Difference: Something that distinguishes one thing from another
* Disparity: A great difference
* Dissimilarity: The state of being different
* Heterogeneity: The quality of being diverse
* Variation: A change or difference in something
Synonyms emphasizing abundance:
* Abundance: A large amount of something
* Plenty: A large amount of something
* Profusion: A large amount of something
* Multitude: A large number of things
* Plethora: A large amount of something
Synonyms emphasizing specific categories:
* Assortment (of colors): A collection of different colors
* Variety (of flavors): A range of different flavors
* Spectrum (of opinions): A wide range of opinions
* Range (of styles): A wide selection of styles
The best synonym for "variety" will depend on the specific context in which you are using it.