Since there’s a unique saturation (boiling) temperature for a given saturation pressure, and vice versa, you can specify either to determine the specific enthalpy and other properties. Your two examples involve multitple saturation values.
Most of the steam tables I have seen start with a column for saturation temperature then the next column gives the associated saturation pressure.
In the first example where the saturation temperature is 75 C the associated saturation pressure in my tables is 38.58 kPa. But the saturation temperature associated with $P_1$ = 50 kPa is about 81.3 C using interpolation. It's not clear to me which $h$ and $v$ values they are interested. The ones for 75 C which are the ones they show? Or the ones for P1 and 81.3 C which would be different.
Maybe you can give us the context of their example 1?
Hope this helps