What is are the differences between a ski jacket and a snowboard jacket?

There is a style difference relating to street wear design made for snow boarding but that fashion trend has become a skiing trend too as audiences moved from boarding to skiing. Some will say board pants are more water proof but that isn't true… buy better quality materials and you get water proof… it's called Gore Tex. Board pants are going to have a bit more reinforcement at its stress points, the knees and hips/butt….places that drag or make frequent contact with the snow. Ski pants will have that reinforcement on the inside ankles, wear the ski would otherwise cut/tear the pant or where the ankles might rub rub more frequently.In jackets, they each serve a function as well. Board jackets tend to be longer with reinforcement on the tail for that extra protection, as well as on the elbows. Board jackets are aerodynamic for boarding… as in sideways to the direction of travel. Ski jackets tend to fit closer to reduce drag around the body, a board jacket catches a lot a wind when facing a mountain like a skier. There is also a lot more movement in skiing, so there is flexibility in the joints and shoulders. Since they don't need the reinforcement like a snow boarder, it can be thinner material to maximize flexibility. Basically, the differences are for comfort of expected movement and they are as durable as they need to be for the task at hand. A boarding jacket might be stiff and would wear out differently if used for skiing and vice versa for a ski jacket used for boarding.You also may not notice any difference in comfort because we rarely use equipment to their tolerances in temperature or weather. If you are comfortable, if its water proof and breaths, then you will do fine with either doing whatever. It will just last longer if built for the sport intended.

Snowboard and skiing jackets are different for two reasons; they’re  aimed at different audiences, and they’re meant for different sports. Skiing comes from a racing tradition, which has always focused on speed and finesse. On the other hand, snowboarding evolved from skateboarding and  surfing…two sports that have always been closely intertwined with style,  street fashion, music, and fringe art. http://www.powderpakoz.com/

No difference in warmth. The main differences are fit and length. Ski jackets are cut to fit like your typical winter coat. Obviously lightweight and traditional style while Boarder jackets tend to be looser and baggier. Almost like they are three sizes too big. Also, they tend to be longer to keep the butt warmer while sitting in the snow while you strap your board on. Edgy style and has Media pockets.

There's a huge difference. A good snowboard jacket, like my company Bonfire makes, is cut completely different than a ski jacket. A good snowboard jacket will also have a higher waterproof and breathable rating, due to snowboarders having more contact with the snow (no poles). In marketing snowboard apparel, your brain would go numb if we went through all the details to make a true snowboard jacket. In particular, there are significant differences in arm hole cutouts and shaping. Very subtle, highly unmarketable, but make a big difference in fit and feel. Snowboard clothes aren't as baggy anymore. That look has been co-opted by free-skiers and snowboarding has moved on.

In a word, fashion.  There really are no functional differences between ski and snowboard clothing.  Jackets and pants marketed by snowboarding brands like Airblaster and Special Blend tend to be more affordable whereas skiing specific brands like Descente and Spyder are much more expensive.  There is an obvious, marked difference in the appearance that this dichotomy in recreation.  The current trend in snowboard apparel are obnoxious neon colours that were popular in the 80s while Spyder and Descente are still preoccupied with the eurotrash aesthetic.  It is, a bit unfair not to point that there are some differences in practical innovation, albeit minor.  I believe there is one snowboard apparel company that markets a special compartment in their jackets for storing drug paraphernalia.  On the other hand I'm sure Spyder make a neat little slot to store your centurion card or whatever.  At the end of the day it might be more prudent base one's purchasing decision on waterproofing capabilities as well as insulation or loft.