Seed or start-up companies are very early stage and pre-revenue. They are likely to be raising funds to develop an idea, product or concept. Investing in a seed company can be risky as they have a much higher chance of failure.
Early stage businesses generally have a tested prototype or service model and have developed a business plan. The company may be generating early stage revenue but might not be profitable yet.
Businesses in the growth stage are in commercial operation with solid traction and existing customers. They are generating recurring revenues and experiencing solid growth, but still may not be profitable.