What is the difference between a nucleophile and a stong base?
This is a tricky one, but to sum it up, nucleophiles tend to be less basic.
Nucleophilicity refers to "how much" a reactant wants to "find" a positive charge. In other words, it measures the instability of the reactant's negative charge.
Basicity refers to "how much" a reactant wants to "find" a Hydrogen ion.
In both of these, the underlying drive is the same--both the base and the nucleophile want to stabilize their negative charge with a positive one.
So, the more unstable the negative charge of a reactant is, the higher its nucleophilicity AND its basicity.
The defining difference, then, is how a reactant behaves in the presence of a substrate that contains an electrophile or an abstractable hydrogen
A strong base will have such a great thermodynamic instability (great energy--such as
A good nucleophile, then, is not as basic and is more likely to be sterically unhindered. Consider
A reactant can be a good nucleophile and a good base and act as either.
As you can see it is very nuanced, and you have to consider the whole reaction when determining nucleophilicity and basicity.
I have to sign off now, but feel free to ask more questions or add more detail.
Hope it helps!