| DistinctByTSource, TKey(IEnumerableTSource, FuncTSource, TKey) | Returns distinct elements from a sequence by using a specified key selector and the default equality comparer to compare values. |
| DistinctByTSource, TKey(IEnumerableTSource, FuncTSource, TKey, IEqualityComparerTKey) | Returns distinct elements from a sequence by using a specified key selector and equality comparer to compare values. |