As a Q&A site we strive for questions that result in a right and correct answer that, ideally, can also stand the test of time.
What might appear as a "simple" question to a poster is often far less so for somebody more informed or the actual specialist.
That lack of specific details will often result in the "too broad" close reason, as a "scientifically correct" answer will need to address too many underlying concepts, variables and considerations that the OP is not aware of. The devil is in the details.
Also a genuinely simple question is often answered by doing a little background research and reading the Wikipedia article.
Simplifying and generalizing your question too much will often make it look completely hypothetical and our community is not always too receptive of those , as the FAQ also clarifies: "You should only ask practical, answerable questions based on actual problems that you face.".
So what triggered your question?
- Academic curiosity? ==> Probably going to be closed as Off-topic or too broad.
- Actual problem? ==> Please edit and improve your question to include the relevant details of your setup as you may have reduced your question to the essentials a bit too much.
As the comments given already indicate, the information in this specific question was insufficient to give a conclusive answer, not only are there huge differences between individual SSD's and between individual HD's, let alone between an SSD's and a random spinning HD, the drives themselves are not the only things that can be a limiting factor, there is for instance also the controller, the IO load etc.
The fastest drives in an external USB2 enclosure are still going to be performing slow in most loads.
An SSD might usually be fast, but possibly there are SSD's (maybe rare, uncommon and designed for specific industrial purposes) that are very slow in every aspect compared to an otherwise already underwhelming 4800 rpm notebook drive.
