Both feeds seem to be fairly similar. I don't believe you'd have a problem feeding either.
If your horse is an adult his protein needs are modest and sometimes the most difficult problem is keeping horses from getting chubby due to too many calories. Most adult horses can do very well on a mineral supplement and just hay. If you want to feed a concentrate to an adult horse, say, in the situation where the hay quality is less, just be sure not to give too much. Most adult horses get chubby on just a few pounds of concentrates a day, unless they're really working frequently.
You can look at the ingredients and percentages for both feeds by googling the products by name.