The 36-year-old former United defender has slammed local rivals City for the way they have inorganically grown over the six years since Sheikh Mansour took ownership of the club.
Silvestre, who played for United between 1999-2008, claims the Premier League champions will never be as popular as his beloved United simply because they 'shut the door' to youth players and buy their way to titles and trophies.
The free agent has told Press Association Sport: "They just buy trophies, United are all about growing players.
"City buy multiple stars and shut the door to the youth system. United have more courage. They are a club with a family spirit.
"Those who come through the ranks absorb the mentality, the history of the club so they show the heritage in their performances."
It's true that City have spent millions upon millions since the billionaire Sheikh took over in 2008, and that spending has resulted in winning two Premier League titles, an FA Cup and a League Cup.
But isn't it the nature of football these days that to be successful you have to buy the best players?
And it's not as though United themselves haven't spent significantly over the years either. £30 million was spent last summer, and £60 million has gone already this window with more spending promised to be on the horizon.
Producing footballers good enough to play at the level that City's and United's first team play at is a rare and difficult thing to do.
United might be a bit better at doing it than City with the likes of Jonny Evans, Tom Cleverley and Danny Welbeck consistently featuring in the first team over the past few seasons.
But it's very doubtful that players of this calibre could lead United to success in future.
Silvestre goes on to claim that City's hefty spending puts potential fans off supporting them, and that their support abroad is nowhere near as manic as United's is.
"The way they do their business, it doesn't get people to support them.
"They might win trophies here and there but they won't gain support. I have been travelling a lot for United in the last six months.
"I have been to Asia, and the support there is unbelievable and honestly City is nowhere near that."