Oh I think being a SAHP is totally exhausting, I wasn't this tired when I worked LOL! My 14 mo is busy busy busy and sometimes I daydream of taking her to daycare and working again, just to get that break from her!
I don't think as working mom I did as much housework, because the house stayed clean more, I had less dirty dishes,etc because we were out of the house all day long. I did stay up late everynight getting things ready for the next day, and the rush in the morning and evenings was tough, but as a SAHM I do those too anyway, plus all the non-stop housework in the daytime from having 3 kids home all day.
Though when I worked I had the major stress of not being to be in 2 places at once, I loved my job, then someone was sick, or it was "Muffins with Mom" day at school, or an art show during school hours, etc. Sometimes you just can't do it all. That was hard for me to realize.
We are military and also have no family support, so maybe matters.
Both are tough for sure!