Different corporate structures.

The main difference between an LLC and s-corp.

LLC- Limited Liability corporation Entity which limits the liability of the owner to assets that are owned by the LLC.  Can protect you from lawsuits and other potential liability.  They are very easy to set-up, although I recommend using a good attorney, who will protect you.  If not set-up properly another good attorney can pierce the corporate veil and come after your personal assets and income.

Tax:  In a single member (owner) a LLC disregarded for federal tax purposes and revenue and expense are shown on Sch C, E, or F if owned by individual (depending on the source of income).  Multiple owners will file a partnership tax return.  The income from business activities (rents and royalties aren't included) is usuallly subject to SE tax if member is an active (participates in business).  The LLC doesn't pay any federal taxes, all income flows through to the owners tax return.

These are great for owning interest in real estate, mineral interests, and other royalty income.

These can have unlimited number of owners and can have different ratios of of share of profits and losses and capital ownership

An s-corp is a corporation, is taxed similarly where it doesn't pay any federal tax, and the owners are taxed on the income of the Corp.  Here you would normally not pay any SE tax, although an active owner in an S-corp with profits would be expect to pay themself as an employee (that income would have SE tax paid on it).  There are also rules to prevent someone from using this for the sole purpose of reducing their SE taxes.

The profits, loss and capital percentages must be equal, and I believe that their cannot be more that 99 owners.

This is great for a larger complex businesses that are closely held. 

The main advantage of both of these entities over others are they eliminate double taxation and provide liability protection