Three terms get used as if they were the same desk. They are not. The difference is not the person, and it is not the rate. It is what each one owns.
An assistant, virtual or in person, works task by task, at your direction. Inbox, calendar, data entry, errands, social posts. You hand over the work; the assistant hands it back done. Nothing moves until you move it, and the list is only ever as good as the one you wrote. Choose an assistant when what you need is hands — more hours in your day, for work you can describe in a list.
A coordinator takes a real estate file and processes it: the documents, the deadlines, the brokerage compliance uploads, the updates between the parties, from contract to closing. The scope is the file, and the arrangement is usually per file. Choose a coordinator when deals are the bottleneck and the paperwork is what is slipping.
A back office runs the whole operation the file sits inside. The listings as well as the deals. The client communication as well as the documents. Every party briefed before they have to ask, every deadline tracked before it is close, and every date and document visible to you at any time in your Docket. It does not wait for instructions — the system runs ahead of the file. Choose a back office when the practice itself needs running, and the paperwork is only part of what is sitting on your desk.
Ask who notices a deadline first. If the answer is you, you have help. If the answer is them, you have an operation.
One more difference, and it is the one clients notice. An assistant is invisible to your clients. A coordinator keeps a deal moving. A back office is felt — introductions, updates, and closing correspondence at a standard your clients can feel, from the first signature to the closing. That is the part that lasts.
Same industry, three desks. None of them is the wrong choice; they are answers to different questions. The only mistake is hiring one and expecting the work of another.