Delta vs. Delta Solar

Hello. Is there a difference between Delta and Delta Solar, apart from the obvious known differences? I mean, is the hardware newer, or is everything the same, except the power glass? For me, (I owned the Fenix 6 and Fenix 6 pro solar), the solar was faster, so maybe there is an upgrade in the Delta hardware also ... Or just had better optimization and the same original few years old Fenix hardware. I hesitate between the two delta models, solar is not an important feature for me. Thank you for your attention