Im a CPA with rentals and i do my own taxes.
I think your question is a little too vague to answer exactly but ill give it a shot. A lot of the tax situations depend on whether you are considered an active or passive real estate investor. When you are active (there is a strict definition of this in terms of hours etc) you can actually use all expenses or losses to offset your ordinary income; such as if you are a real estate broker and have rentals. Whereas if you are passive such as have a regular 9-5 and do real estate investing on the side you cant use losses on your rental to lower your taxable income from your regular job(to a certain extent). You can have a loss on your real estate rental even if you cash flow because of depreciation. Depreciation isnt an actual money cost but its an expense for tax purposes. Rental income is "tax advantaged" income because you can offset it by depreciation and other expenses to ultimately sometimes not pay any taxes in that income.
The other tax benefits are that normally when you buy something low and sell it high, such as stocks, you will owe taxes on the profit. However, with real estate, if you take that gain and use it to purchase more real estate, you can delay paying taxes on that gain(sometimes never having to pay it if you keeping buying real estate when you sell) through a 1031 exchange. This isnt only used in real estate but for the layman it may be the only place they use a 1031 and it is a benefit that isnt applicable to a 9-5 income.
Tax deductions for mortgages aren't really a benefit over anything comparable because anytime you have a loan for business whether its real estate or not, you can deduct loan interest on your taxes.