Difference between "whereby" and "in which"?

Are there any differences between them? For example,

Conversion is the process whereby a value of one type is transformed into a value of another type.

Whereby is another way of saying by which. It denotes the means by which something occurs.

In which, however, denotes the place or process in which something occurs.

Thus,

'Conversion is the process whereby a value of one type is transformed into a value of another type.'

means that the process is the means by which the value is transformed; however,

'Conversion is the process in which a value of one type is transformed into a value of another type.'

means that somewhere in the process one type comes to be transformed, but the process is not necessarily the cause thereof.

The difference is subtle and most people will likely not notice it, but there it is.