Not sure he really meant to compare his accomplishments with James, but even in size it is indeed like a flea to a T Rex.
That said, yes Jackson will help. The Rams were really missing that speedy deep threat last year. Since Stafford is a superb deep ball thrower, and Jackson a superb deep threat, providing both stay healthy it is going to open up the middle of the field much more for Kupp, Woods, and Higbee.
Still I suspect the Rams are intent on landing a deep threat WR in the draft with Jackson as a fingers-crossed 1 year bridge guy.