I’ll answer using two descriptions.
– Expertise is an amalgamation of experience, skill and ability related to a specific task or domain.
– An expert is someone thought to have experience, skill and ability in a specific task or domain.
Expertise is about possession of skill and understanding. To be an expert is to be perceived as possessing these two things. The two are very different.
Don’t believe me? Consider the truth of the following two sentences.
– Not all experts have expertise.
– Not all those with expertise are considered to be experts.
Which are you? Which are you aspiring to? Expert status or expertise? The possession of skill? Or the appearance of it’s possession?