Closing the EPA would mean shutting down the agency, firing all the workers, and selling off its assets. The current freezes do none of those things, instead shutting down a small number of functions that are not the core of the EPA's work.
The Contract Freeze
According to ProPublica, an EPA contracting officer said:
“Right now we are in a holding pattern. The new EPA administration has asked that all contract and grant awards be temporarily suspended, effective immediately. Until we receive further clarification, this includes task orders and work assignments.”
This doesn't prevent the agency from doing the majority of their work. What it does no new grants or contracts be awarded, as well as put a hold on currently active contracts Task orders and assignments are specific acquisition tools.
However, the ban could become important if it lasts a while. The EPA currently has over 600 contracts. Federal purchasing guidelines often require purchasing from a contracted vendor if one exists, so eventually supplies may run low. The EPA also uses contractors for performing a variety of analyses (for example, analyzing groundwater for traces of contaminants). Until the contract freeze is over, this work will have to wait.
Social Media Freeze
The EPA can still communicate with the organizations that it deals with around the country. This is unlikely to significantly influence how the agency does business.