Why does
Solve[Sqrt[x + Sqrt[x]] - Sqrt[x - Sqrt[x]] ==
m Sqrt[x/(x + Sqrt[x])], x, Reals, Method -> Reduce]
give a different result than
Reduce[Sqrt[x + Sqrt[x]] - Sqrt[x - Sqrt[x]] ==
m Sqrt[x/(x + Sqrt[x])], x, Reals]
note that the first one says $1<m<2$ while the second one says $1<m\le 2$.
The documentation says
With
Method->Reduce
,Solve
uses only equivalent transformations and finds all solutions.