Before you look at jurisdictions, understand what it means to be a city in Virginia. Unlike every other state where a city is part of a county and often serves as the county seat, in Virginia cities are independent from the county that encompass them (
39 of the 42 "independent cities" in the US are in Virginia!). There are also very few benefits of living in a "city" vs an unincorporated area as both are suppressed in what services they can offer to constituents due to the
Dillon Rule.
Manassas City and Manassas Park are independent cities located in PWC. Looking at a map,
Manassas Park is slightly rectangular shaped on the Eastern side of Manassas. Manassas Park used to be part of Manassas, but seceeded in the 70s.
Secession has not been kind to Manassas Park, as it is generally poorer than Manassas city. Newer, nicer housing is located near the Generals Ridge golf course and Signal Hill. Don't know about schools.
Manassas city schools I would assess as fair, but they do draw from some unfavorable areas (Georgetown South, some areas off Liberia), but they're not bad.
People may say they are from "Manassas", when in fact they live in the unincorporated areas around Manassas in Prince William County. A lot of the shopping areas people consider part of Manassas are not actually located in Manassas proper, including the Manassas mall. People in the vicinity of Manassas may have a Manassas mailing address even though they are in the county. PWC has good schools and newer housing.
Again, aside from the school pyramid, there aren't many day-to-day differences between living in any of the jurisdictions.