Make shift Available allows other employees assigned to the same location and position as a shift to see that the shift is available for pickup. Employees can apply for the shift and then a manager approves or denies the exchange.
Offer shift allows an employee to offer the shift to a specific employee. Offers can be restricted by location and position like available shifts or management can allow employees to offer shifts across locations and positions. In the Free version of Sling, this function also allows employees to trade shifts. Both employees offer their shifts to each other to complete a "swap."
Swap shift (Premium and Business versions only) lets an employee offer one of their shifts in exchange for another. An employee will offer and request a shift through one function. Like offers, swaps can be restricted by location and position or management can allow employees to swap across them all.
In all three cases, the employee originally assigned to the shift is responsible for it until an exchange is approved. If no one applies for an available shift or accepts an offer or swap, the shift is still the employee's responsibility.
Additionally, if a shift exchange is not approved by management, the original employee is still responsible for working it.