Under Accounts you manager all of your financial accounts as well as cost centers, i.e. the entire chart of accounts / cost center plan.

Accounts [more]
Here you manage your financial accounts, i.e. your chart of accounts.

Cost centers [more]
Besides expense accounts you can review your costs under other aspects. With cost centers you can automate a part of your cost accounting, namely the allocation of book entry amounts or invoice item amounts to cost centers and cost units. This is a PRO feature (not available in the free version).