It is relatively easy to rack up years on the job. A year, two years, and a decade can flash by.
Experience, on the other hand, is so much more than years on the job.
Experience is the pattern recognition that comes from having worked through a broad array of problems. It is the collection of the mental models that you develop after having synthesized every experience to complement that breadth with depth. It is many inches wide and, yet, somehow many miles deep as well.
A simple proxy for experience is the presence and constant accumulation of skills. Another telltale sign is the presence of rigor, synthesis, and obsession.
When you live the same year many times over, you rack up years on the job.
When you compress three years of learning into one, you gain experience.