You could ask a CFP. They can help to...

It seems you are most interested in the tax part so

For an S corp the income or loss flows thru to the shareholders, which would be you the business owner. This can be a big advantage for a new company as most new companies have losses early on that the business owner can use to offset income from other sources. I tend to believe the S corp model has a limited useful life in this regard. Once the corp is profitable the income will flow thru and be taxed at the highest marginal tax rate of the business owner. On the other hand if your business continues to experience losses and to the extent those losses exceed your basis, you cannot write off the loss. Also, b/c the flow thru of income is not subject to the self employment tax you have to make sure you give yourself a "reasonable salary" according to the IRS. There are other considerations such as how you calculate basis but these are some of the bigger ones. If you are converting from a C corp you have to watch out for things like LIFO recapture and built in gains as well.

For LLC, if structured the right way, will basically merge the limited liability of corps and the same tax treatment as partnerships. An LLC that has only one member will be a disregarded entity for federal income tax purposes and treated exactly like a sole proprietor. With more than one member, taxation is exactly like a partnership (income and loss flow directly thru to the owner), but you can elect to be taxed as a corporation.

The key differences between the two are more related to their structure requirements.

Before you decide on the right structure for your business you should look into liability protection under each form, business continuity, formation and operation as well as tax issues.