Non-profits don't necessarily have to spend all their income by the end of the year; they just have to report it if they had anything left over. I've already reviewed a number of non-profit "church" organizations who have assets listed.
Yeah, there are plenty of differences between a business and a non-profit. The first and most obvious is that businesses are not tax-exempt; they pay taxes just like the rest of us.
There are no problems with owning a business in the U.S., and I want to emphasize that in case other people are reading this. There's nothing Scriptural against owning a business. I would say the problem is when a church or evangelistic ministry becomes a business, in which they start charging people money for what they produce. Please don't misunderstand; if someone wants to start up a business to sell materials, that's not a problem, but my conviction is not to force people to pay to view that material if the material is preaching Christ's doctrine and philosophy.
If you're asking about filing the church as a business, personally, I wouldn't support someone who does that, any more than I would support the merchant tables setup on the steps leading up the to the Temple in the days of Christ. However, there are others who start up their ministry and/or church, and then start up a business on the side, and that's completely acceptable in my opinion; just be careful for the ones who charge you to view their materials, whether they be video, audio, or books.