CRMs organize and manage customer-facing interactions and they are particularly useful to sales teams. Eg a customer has enquired about a product, which of your products they have bought etc.
CDMSs are a little wider and could tell you each specific step that a customer has taken since interacting with your company, from the channel they found you on (eg internet) to how they use your product etc
I don’t think in practice and for this question there is any important distinction.