Generally not. Upon return from FMLA leave, employees must be restored to the same job or one nearly identical to it with equivalent pay, benefits, and other employment terms and conditions. To be truly equivalent, the job must involve the same or substantially similar duties and responsibilities and require substantially equivalent skill, effort, responsibility, and authority. Equivalent jobs would also have the same premium pay options and overtime opportunities. So, unless you can guarantee that the different role is equivalent to the old one in all these ways, we wouldn’t recommend placing the employee in a different role.
There is, however, a notable exception. Employees on FMLA are not protected from employment actions that would have affected them had they been actively employed with the company at the time. For example, if a substantial decrease in sales required a company to eliminate a set of roles and lay off or transfer those employees, the person on FMLA has no greater right to keep their job than anyone else. In situations like these, where a position has been eliminated while an employee is on a protected leave (of any kind), you should be sure to document your legitimate business reasons for the decision.