I had 4 Flemish Giants in the past 10 yr. My impression is, when they are young, they are hopping around like monkey, when they get mature, they are much more relaxed.
Although my 3rd Flemish Giant, Little Happy, (male) was restless bunny, nosing around in his entire life. The other 3 so happened to be all female.
Having said that, I now one Dutch bun, Minnie, and 1 Silver Marten, Bernie. Quite honestly, the Dutch is about the same as the Flemish Giants that I had, quite relaxed and don't hop much during the day.
However, one big difference btwn. Giants vs. Dutch say, is that when they run in the backyard, Minnie run a lot faster, and she can do all 4 feet off the ground. Giants can't do that.