The difference is the degree to which the team is set up to rely on Kane and Son for scoring. No Spurs player other than those two has a non-penalty xG >1. Literally, nobody else is getting into scoring positions frequently enough to have been expected to score more than 1 goal this year. Not their wingers on the other side, not their most advanced midfielders, nobody.
In comparison, Liverpool and City have six such players, Chelsea and United five.
Kane and Son are both elite players but their scoring is unsustainable and when they hit a bad patch of finishing form or Kane gets his annual 6-8 week injury they will be in trouble unless Jose switches tactics so that the team establishes other ways to score goals.