Definition in dictionary:

VARIATION

1. a change or slight difference in condition, amount, or level, typically within certain limits.
   “regional variations in house prices”Synonyms: difference, dissimilarity, disparity, inequality, contrast, discrepancy, imbalance, dissimilitude, differential, distinction More

2. a different or distinct form or version of something.
   “hurling is an Irish variation of hockey”Synonyms: variant, form, alternative, alternative form, other form, different form, derived form, development, adaptation, alteration, modification, revision, revised version
   “he was wearing a variation of court dress”

SIMILARITY

1. the state of being almost the same, or a particular way in which something is almost the same:
   “the similarity of symptoms makes them hard to diagnose”
2. a similar feature or aspect.
   “the similarities between people of different nationalities”Synonyms: resemblance, likeness, sameness, similar nature, similitude, comparability, correspondence, comparison, analogy, parallel, parallelism, equivalence; interchangeability, closeness, nearness, affinity, homogeneity, agreement, indistinguishability, uniformity; community, kinship, relatedness; archaicsemblance
   “the similarity between him and his daughter was startling”