You must contrast the two funerals as there isn't much to compare.
Willy Loman's funeral ceremony was attended by only his wife, two sons and his neighbors. Out of these five individuals, how many respected or even liked him? Charley and Bernard both felt pity for Willy. Happy seems to be indifferent toward his father. Biff still holds some resentment against his dad. Willy's wife? Does Linda love him or is she an enabler, unwilling to face the harsh truth of Willy's failures?
Dave was everything that Willy wasn't: a success. Willy says it himself, "I'm not liked." People did make fun of him in the business world as he had to work twice as hard to sell half as much. Willy was in the wrong line of work.
Dave has what Willy dreams of in a funeral and never will have: a room full of fellows salemen and admirers who talk whistfully his life and success. Willy's funeral is attended only by his immediate family. In Act 2, he tells Howard about the late, great Dave Singleton's funeral:
"...when he died, hundreds of salesmen and buyers were at his funeral. Things were sad on a lotta trains for months after that. In those days, there was personality in it, Howard. There was respect, and comradship, and gratitude in it. Today it's all cut and dried, and there's no chance for bringing friendship to bear -- or personality."