- There is work to do.
- There is work to be done.
I'd like to know whether they are different in meaning or not.
Yes, they mean the same thing. In both cases, the person who is responsible for doing the work is left implicit.
For example, if the person is you:
There is work [for you] to do.
There is work to be done [by you].
Another sentence that also means the same thing:
You have work to do.
The name or pronoun may be omitted as in your examples for a number of reasons, e.g. for politeness ("You should be working right now" is less polite than "There's work to do"). Depending on the context, it might not be clear who is responsible for doing the work. In that case, it can be interpreted as "There is work for someone to do". You can use these constructions for speaking abstractly about the work that needs doing. The second example ("There is work to be done") is even less emphatic about who is responsible.
They are essentially the same and would tend to be used interchangeably, but there's a nuance of difference. Do refers here to activity that will happen in the future. Done refers to bringing something to an end or finish; it is something that will have happened in the past.
There is work to do is open-ended. It can be little tasks or just making progress on big projects that will take forever to complete. It focuses more on activity; doing things to at least make progress (and can include tasks that will be completed as a result).
There is work to be done suggests the completion of tasks. Making progress on a long-term project usually involves breaking it down into small pieces, so you can talk about completing chunks of it. The perspective is that at a later time, you will be looking back at completion of tasks, so it suggests a focus on completion or accomplishment rather than activity.