are the individual distributions of the small and large components.
Given this your probability of the smaller component being larger than the large component is just the 2D integral of the product distribution over the area where s > l, i.e. the area below the line s=l.
for example in the image above you integrate that 2D Gaussian over the blue area.
Depending on what your individual distributions are you may be able to use functions that exist in Excel to do the integration directly. Otherwise you have to somehow make a table of the 2D distribution and apply your favorite numerical integration method.