Experienced hire simply means that you are hiring candidates that have worked and held a full-time job before. This can either be industry (e.g. worked at Procter&Gamble) or boutique/different type of consultancy (e.g. BTS consulting). "Lateral" transitions between strategy consulting firms (e.g. Bain to BCG) are quite rare so it would depend on the specific instance whether the candidate is treated as an experience hire or not.
A further requirement is that the candidate usually has to have worked for at least ~2 years to be considered experience hire. Shorter than this, candidates usually have the option of applying through the regular, "graduate hiring" cycles.
Key differences between graduate hires and experienced hires:
- In terms of recruiting, consulting firms likely have separate teams for both, since consulting has a very different appeal for someone straight out of university vs. a finance manager at a F500 company
- Experience hires can enter at many different levels based on experience. For very senior hires, they may enter as a Manager or even as a Partner (e.g. if you hired the COO of a division at a client). More junior hires could enter at various levels, based on both their experience and their ability to negotiate. In some cases, hires might be hired at a very junior level, but with the possibility of "fast track promotion" if they perform strongly.
- Experience hire recruiting goes on year round, graduate recruiting generally happens once a year
- Depending on specific experience, experience hires are more likely to align to a practice right away vs. graduates
Hope that helps clear this up!