In the concept phase you are still in the ideation phase and might not have a clear company structure. Often looking for inspiration, how-to knowledge and partners/co-founders.
In the Seed stage you are starting the process of vetting your idea and doing ideation, prototyping and potentially an MVP. Commonly looking for seed money to start operating the business.
In this stage your idea is validated by third parties. You now have the resources/funding to develop your product/service, infrastructure and team. You are optimising your business model and looking to get paying customers.
You now have a paying customer-base. You are looking to grow sales and find new opportunities for market penetration. Often looking for larger investments and talent. May also be called scale-ups.
In the Mature stage you are comfortable with your business model and have a solid customer base. In these times it’s interesting to expand your business in terms of products/services and expanding to new regions/countries. Often looking for R&D, flexibility to pivot and talent retention and acquisition.
Note that it’s rarely a 100% clean cut which stage you are in. So when choosing what Business Stage you are in, say the one that applies the best to you.