We called it Bloodweed down here in South Texas and looks like what you have in that pic. It is very stemy and grows 10-12' tall on the creek bottoms here where it is wetter and no cattle on the places. Gets full of ticks at times on the bottomland sites. I think Giant Ragweed is the correct name and is also called Bloodweeds in this area. They are one in the same I think based off your photo and link.
Better get it done QUICK. I just mowed a portion of one pasture this morning that I haven't been able to get to before....because it was too wet.
In East Texas everything grows fast. If you look the other side of my tractor in the pic you will see the weeds I am mowing. Some are a full 12' high.
I had to take out small strips as I neared the fence-line....because I literally could not see the fence itself...it was so thick.
Yes, I believe your observation is correct (known by different/several names).
'Bloodweed' in Deep East Texas is a colloquial term assigned to Pokeweed...which has dark purple berries and a reddish stalk/stem.
It is in error that it is called Bloodweed. Not unlike Rat snakes which are always called Chicken Snakes here. I attribute that to being so close to Louisiana where they have a bastardized name for virtually everything.
Some of that has seeped across the border.