Difference in "heat capacity rate ratio" and "heat capacity ratio"

[max3-2]

Hi,

as the title says, both the terms heat capacity rate ratio and heat capacity ratio seem to be used in the documentation. Can someone elaborate on if there is a difference or both is the ratio of (m * cp)? I feel like publications are also not always clear.

On a connected sidenote, sometimes this is specified with ...with respect to stream 1 - does this mean that stream 1 is in the denominator?