Not really...
Steeping grains like Cara/Crystal malts or other Dark malts are usually "steeped" for their sweet or robust flavor and color contributions. They have already been converted to sugar so they do not need to be mashed. Think of it like a tea bag in water.
Partial Mash beers contain unconverted grains, high in starch (which must be converted via a mash - which is nothing more than a very stringent/controlled steep that focuses on exact temps/times/ratios/etc). These grains include 2-row, wheat malt, munich, vienna, rye, oats, etc. They are not rich in caramel sweetness or very dark, raisiny, roasty.
A PM beer usually contains 50-60% Extract such as LME/DME (which is basically base malt that has already been converted). So a partial mash beer is approx. half grain that has not been converted (which needs to be) plus approx. half extract that is ready to use.