Anything with oil in it will darken with age. On the surface of it, they don't look like they would be that disparate. I agree on dye, although am not fond of water based because of grain raising.
If I had to color tabletop, I imagine I'd spray Homestead's Transtint diluted in alcohol. Really light concentration to begin.
Also, not sure about Osmo, but Waterlox has definite brown cast when viewed in the can. So it shifts color some. To my eye the yellow/brown shift does some really nice things for walnut, which can look a little gray without adding some warmth.