AW is the last generation litium complex, XHP is the next generation. They are compatible, based on the ExxonMobil internal method. The base oil vis is higher, which means it's not a straight swap if you need to compy with GM's absurd LS2 requirements. If you have to comply the LS2, the direct replacement is Ronex MP, otherwise you'll be at least as happy with XHP as with AW.
Grease compatibility is primarily a function of soap type, but even that is getting fuzzy. As the complexing of soaps gets better, some of the historic "don'ts" are going out the window. Especially the Li-complexes - they seem to go with everything, Al-complex, polyurea, clay, incompatible results seem very rare, but what would I know?