Any Example of reusing one component A to make 90% identical component B ----> Most preferrally how we can do by using sling script resolution scheme ?
Make Component A as parent(sling:resourecSuperType) to Component B.
You can do this via AEM's component building concept, overlay. An example is what you asked, there's an old but effect video from youtube where you can see learn how to create an overlay component, https://www.youtube.com/watch?v=jmzLzvtCSWY&ab_channel=AEMandDevopsTutorial
Its same as we inherit any core component, so to reuse something u need to inherit the component and add the changes required for that component.