A mandate would be a religious test that requires someone to take on oath saying you believe a certain way in order to obtain a government privilege like a job/position or to graduate or to drive. A mandate has some sort of punishment element. An acknowledgment would be to recognize religious holidays like Christmas and Easter and to allow displays like manger scenes and to allow religious prayer or speeches at events such as a graduation. An acknowledgment would have no sort of punishment element attached and no requirement to participate. Just being exposed to it would not constitute a requirement to participate.
Currently, exposure of a majority belief to a minority belief is considered coercive and sometimes banned, but exposure of a minority belief to the majority is not, which is an odd and an extreme interpretation.