Well, somewhere in the middle there. Replicators don't convert energy to matter - they use transporter technology to recombine existing matter into different forms at the molecular level. You still need a matter store that contains the correct types of elements - no high-tech alchemy involved here.Rather large. Food synthesizers create food from a store of raw materials. Replicators create matter from energy and are not limited to just food.
What we saw in Discovery may have been a full-on replicator, or it may have been a precusor to that technology, perhaps weaving existing molecules together at the microscopic level - which is about the same tech level as TOS food synthesisers. We don't get a sufficiently detailed explanation of the technology to say for sure.