This is by analysing the information provided on the boxes of both tools. As 2045 is longer, does that mean it has longer knife too? I don't think that will be the case but still will be good if someone can confirm that
If those are the numbers on the box, either they're incorrect or BIBURY has sold multiple tools with the same model number and different physical shapes.
2045 (left), 2049 (right):
Leatherman Surge, BIBURY 2045, BIBURY 2049, BIBURY 2038, Leatherman Charge:
The major difference between the 2045 and 2049 is the visual style of the handles (Skeletool-knockoff design or Free P2/4-knockoff design; to be clear, mechanically, they both work like a Surge -- the styling is purely cosmetic) and the attachments that come with each. (See the $150 EDC thread linked above for a picture of both and a description of what they come with.)