What gross profit can tell you
Since gross profit is an absolute number, it is somewhat less useful as a comparison tool for investors than gross profit margin, which is a percent. Investors can more easily use the gross profit margin metric to analyze and compare companies.
However, you can better understand a company's gross profit by closely examining its COGS. Product businesses usually have higher COGS than service businesses, meaning that product businesses generally have lower gross profits. But service business usually have higher operating expenses than product businesses, so higher gross profits are necessary for service businesses to pay for fixed costs such as insurance or marketing.
If two similar companies with similar revenues have much different gross profits, then the company with the higher gross profit likely has some significant competitive advantage. If a company's revenue over time stays constant but its gross profit sharply declines, then one or more of its direct costs has significantly increased. Sometimes a company's COGS stays constant but its gross profit drops because the price the company is able to charge for its product or service has substantially declined.