Asana is a prerequisite for Pranayama.
There are several types of Pranayama and Asana.
Is the effect same in the following two cases
Doing any type Pranayama with any Asana
Doing a particular type of Pranayama with a particular Asana
If the effect is different, then an example of achieving something with only a particular type of Pranayama with a particular type of Asana can be an answer.