What's the difference between pulsing and throbbing? (PMs welcome!)

My cock pulsing and throbbing as I cum twice

Handsfree pulsing and throbbing cum

Why yes, I’m using a vaginal electrode to train myself to have

Throbbing Closeup

Pulsing and Throbbing

Pulsing & throbbing when I think of you

Throbbing and pulsing after the job is done

throbbing and pulsing

(62) imagine my gorgeous cock pulsing and throbbing before it

A Massive Throbbing Cumshot!!

throbbing and pulsing