What is the difference between spider poo and spider eggs?

I just saw the largest spider of my life crawling on my bed and snagged it on my pillow. Just before I grabbed it, it shot white liquid out of it's backside and I couldn't tell if it was laying eggs or dropping waste. I couldn't figure out what it was online and wasn't about to go grab a glass to trap it and worry losing it. It seemed to be identical in size and shape to a Black Widow; however, it was a light solid brown throughout and had no red dot on it. So I also have no idea what it was. I just know it scared the hell out of me and wanted to get rid of it before it bit me or reproduced.