Which one takes less time to manage?
On the surface, long-term rentals are much more passive than long-term rentals. With Airbnb, you have to communicate with prospective guests, communicate with existing guests, constantly market the property, constantly turn the property, maintain utility contracts, replenish consumables, maintain the property, and maintain the furniture. All of that on a fairly consistent basis.
With long-term rentals, you have to do many of these processes, but most of them are on an annual or quarterly basis. With good systems, the management starts to approach parity on a per-unit basis.
Short-term rentals are a hospitality business as much or more than a real estate business. As such, you will be interacting with people more and in more interesting ways.
With long-term rentals, you can pretty much get a place habitable and then lease it out. The level of required amenities is quite low. I don’t recommend offering a bottom-of-the-barrel product as a rental, but it is possible. With Airbnb, there is much more setup involved. You have to meet certain community standards at a minimum.
If you plan to add capital to your real estate investment pool quickly, then scalability might be essential. If you grow your portfolio at a few units per year, scaling short term probably will not present any major management problems.
It’s probably no surprise that renting a place completely furnished with a few sets of linens and a stocked kitchen would have higher startup costs.