Variety, Variation, Variant, Variance

This post is actually for me, but who knows, maybe some people out there need it also. At first I was a bit confused whether to use the word ‘variety’ or ‘variation’ before the word ‘people’. Then, as always, I googled the differences and found more than just the explanation from ‘variety’ and ‘variation’. All of the words mentioned later are NOUNS.
1. Variety
The word ‘variety’ means A DIFFERENT TYPE OF SOMETHING. To be exact, one certain thing can have some VARIETIES. For example, the fruit APPLES, can have some varieties such as RED DELICIOUS, JONATHAN, GRANNY SMITH, FUJI, etc.
2. Variation
‘Variation’ means A CHANGE OR SLIGHT DIFFERENCE IN CONDITION, AMOUNT, OR LEVEL FROM THE USUAL FORMS. For example, “She added some new variations on the choreography” means that she had the same choreography, only it was improvised, perhaps by adding some new moves.
3. Variant
According to Concise Oxford English Dictionary, ‘variant’ is a form or version that VARIES FROM OTHER FORMS of the same thing or FROM A STANDARD. Or, as what I read from this page, ‘variant’ is something which is SLIGHTLY DIFFERENT FROM OTHER SIMILAR THINGS. For instance, ‘theatre’ is the VARIANT spelling from ‘theater’; Bulimia is a VARIANT of anorexia.
4. Variance
I found the definition of ‘variance’ here. It says that ‘variance’ is the state, quality, or fact of BEING VARIABLE, DIVERGENT, DIFFERENT, or ANOMALOUS.  The word ‘variance’ is usually used in phrase ‘at variance with’. As an example, her income is AT VARIANCE WITH her expenses.
In conclusion, the differences between ‘variety’, ‘variation’, ‘variant’, and ‘variance’ can be illustrated in the following graphs.
Whoo! You have no idea how long it took me to illustrate the differences. I hope this helps, and correct hehe. If there are some mistakes, please feel free to comment and correct. Thank you.