Teams all build their cars based on the rulebook, so every team has a different chassis, aero, etc. Currently only Mercedes, Ferrari, Renault, and Honda/Red Bull manufactures engines, and they supply the teams on the circuit.

For example, Ferrari supplies engines to Haas and Alfa Romeo. Honda/Red Bull also supplies engines for Alphatauri. Mercedes supplies engines to Williams and McLaren...

This year budgets have been limited, so teams have a finite amount of money to spend on wind tunnels, development, etc. I think that's the reason we have much closer performances by the teams this year.

In a couple years, there will be several more companies supplying engines, buying into teams, etc. Audi and Porsche have made official announcements they are entering F1. I think there's at least one other company planning to enter, but we shall see...

In the past, when a team threw the most money at the car, they dominated F1. See Ferrari when Schumacher drove for them, and Mercedes up until this year. Both cars were significantly superior to everyone else. That's one of the reasons Michael and Lewis have so many F1 titles.

Right now there are three teams who are/will be driving for wins before long...for too many seasons there has only been one team who had a 95% chance to win (See those Ferrari and Mercedes strings of championships).

It's the pinnacle of motorsports, and there are no other cars that are anywhere close to the speeds F1 cars on tracks...and it isn't close.