Not the same. Steeping grains don't normally contain grains that have active enzymes. The temperature range for mashing is fairly narrow whereas steeping is 32 to 170 degrees.
Here's how you could do a partial mash if all you are set up for is steeping grains. Take your oatmeal and combine it with an equal amount of ground 2-row or 6-row in a steeping bag along with your steeping grains. Put that into your water and heat it to around 152-155 degrees. Turn off the heat and let it be for an hour. You will have to apply a little heat and stir every 10 minutes to try and maintain the temperature. You can wrap the pot in something to insulate it.
The enzymes in the malted barley will convert the starch in the malt and in the oatmeal during the mash into fermentable and unfermentable sugars. Once you are done, proceed with your recipe as if you had just steeped your grains.