Wallace was an outsider, and the son of a laird a step up from a commoner back then. Remember too, he didn't have the clout or the training that Moray had. Yet he rose through the ranks to become a knight of the realm, and the guardian of Scotland at one time. You don't do that by leading a combined force and basking on the shirt tails of Moray. Knighthoods were not dished out like they are now, to luvvies, sportsmen and other 'heroes.' Scotland was fighting for survival, it couldn't afford the luxury of hangers on.
Although they probably knew/fought together, Bruce and Wallace had different aims. Bruce had one eye on the Crown, whereas Wallace was fighting on behalf of Toom Tabard, a prisoner of Edward. Wallace was executed in 1305, a year before Bruce was crowned. I don't think it's to much of a stretch for Wallace to be knighted by Bruce. He'd been campaigning successfully, against the English before meeting up with Moray. With TT captive, Bruce was high enough up the pecking order to knight Wallace.
Then we come to a certain Edward Plantagenet, Longshanks, the Hammer of the Scots, one helluva warrior King. During all the kerfuffle between us, Edward forgave many former foes. No such hand was extended to Wallace. After 30 pieces of silver had changed hands Wallace was whipped down to London, tried and executed for treason. Do you really think Edward would persecute a nobody for years, unless he, not actually feared him, but realised the danger of letting him live?