You have probably compared Udemy and Coursera by price and decided Udemy wins. But price is the smallest difference between them, and choosing on price alone is how people waste money.
Udemy sells individual courses you own forever, taught by independent instructors. Quality varies wildly, so the course you pick matters more than the platform itself.
Coursera sells structured programs from universities and companies, with graded work and recognized certificates. You follow a path rather than assembling one yourself.
The rule is simple. Buy Udemy when you know exactly which course you want and the reviews are strong. Choose Coursera when you want a guided, credential-backed program. Different tools for different jobs, and both are good at what they do.