Assume company A sells a widget for 10 silver
Then company B comes along and sells same widget for 3 silver. Company A will either learn to be more efficient and sell at 2-3 silver, or go out of business.
Capitalism is not the same as free market; capitalism is rather a system where your economic power is mainly determinated by the amount of capital you have (money, investments, means of productions...) rather than class, bloodline, titles, popularity, or legislative regulations[2].
Capitalism is linked to free market in that they work well together: free markets want enterpreneuers to be compete for efficient capital gains and people with capital like how their economical power is only bounded by their capital (with the potential of an exponential growth). Apart from this ether can exist without the other.
This is how supporters would like them to work together, but there can be a lot of bugs and traps on the way.
[1]: https://slatestarcodex.com/2014/07/30/meditations-on-moloch/
[2]: This last one would be the characteristic of planned markets
By the time the market wakes up you’ve switched 3 times and after 10 times you’re retired in the suburbs with a nice BMW. Who cares then.