Marchand has won gold on a WJC team and has shown great offensive potential in the juniors before making the NHL. Friesen, on the other hand, has not yet shown that offensive promise to be a top 6 player. I think naturally, Marchand is more talented offensively than Friesen, and that's why he won't be as effective as Marchand in that category - if that was what you were looking for.
However, Friesen has shown more intangibles than Marchand - namely, leadership and grit. Marchand plays a role of a pest who gets under people's skin, but will not stand up for himself or fight most of the time. Rather, he plays to draw a penalty. Friesen, on the other hand, will rock you with a solid hit and isn't afraid to drop the gloves to protect himself or his teammates.
I think Friesen is more comparable to Mike Peca than Marchand - an honest, hard-working player who isn't flashy offensively but can chip in here and there. Friesen could end up on the top 6 in his prime, but he would be an excellent top 9 forward down the road IMO.
I look forward to watching him destroy Taylor Hall in the NHL too.
I think this video should quiet any doubters who think Friesen's size is an issue for him. Taylor Hall was deemed the most NHL ready prospect that year, and Friesen is able to man-handle him with that hit. He plays an intelligent game and though not a big player in stature, he plays big and makes most of his opportunities due to his intelligence.
Hall made the NHL the very next season - I'd imagine that Friesen then too is NHL-ready physically by now. All it takes now is the hard work to get caught up to the speed of the game at the pro level and learn the system - and with his work ethic, I think this would be a rather quick process. I could see Friesen surprising quite a few people in Chicago this season.