As they are supposed to in the fluff he towers over normal humans. Space Marines in full armor are supposed to be around 8 feet tall, which means that a normal human should only come up to the mid abdomen/bottom of the ribcage.
The real difference though is just how massive he is width and girth wise (that's what she said...). According to the backstory the thing about Space Marines which always awes normal humans is their shear bulk and presence, its like being an 8 year old standing next to a football linebacker.
And you can see just how "puny" a normal space marine model looks by comparison. It will be interesting when I eventually try my hand at making terminators to this scale.
Oddly he's about 1.33 times the size of a normal space marine if anyone was wondering what ratio I used in his creation.
Main post with my rambles is here: [link]