You need lots of mech play for protoss. Vultures/Gols with tanks (lots of tanks) with 3/3 upgrades is pretty tough to break. If you can secure a 2nd base, you can comfortably produce out of 5 or 6 factories.
Zerg needs lots of map control with hydras, lurkers, and defilers. It's a bit harder in terms of having to bring your attention to lots of areas. Generally the protoss have it harder to overcome.
Protoss vs protoss you just need more units than they have when you attack.