I ask this question because there are real differences in what you are allowed to deduct, capitalize and report in these two situations.
Investors that are wholesaling and flipping are typically in the business of real estate.
Landlords typically are not in a "trade or business" as defined in the IRS code & regulations, but are engaged in an investment activity (Production of income).
Deductions that are reasonable and necessary in the production of rental income are not necessarily the same as what would be considered reasonable and necessary for a business.
A business would be allowed research and development costs, educational Seminars, trade shows, meals and entertainment. In the production of rental income you would in most cases have a tough time making a case that these were reasonable and necessary expenses.