Reynolds number

Hi, this is going to sound very stupid.
Is Red the same as Re?
Its just that in some equations, I have Red, and then in others Re. It might not sound like much of a problem, but I'd really appreciate if someone could clear things up for me. Thanks!

Reynolds number with a subscript usually pertains to the RE with respect to a particular characteristic dimension of an object. For example, in a lot of problems looking at flows past flat plates, you will see $$RE_x$$ for the RE along the length of the plate measured from the leading edge of the plate. Perhaps the usage in your case is the flow past a cylinder or sphere.