The Variations and Fugue was written in 1884. The revised version, the Variations, was completed in 1922. Actually the fugue was not discarded, but transformed and abbreviated into one of the variations.
The Variations (1922) is one of my favorite pieces (this is the version that I was first acquainted to, so I may be a little bit biased against the 1884 version, which seems long winded). Anyway, this piece has a nice blend of classical style and 20th century sensibilities.
Interestingly it shares the same opus number (Op. 22) with Rachmaninov's own Chopin Variations.