Under the capitalist system, producers produce the goods that they think consumers want, then if consumers buy those goods, they make more of them. Under a free market, each producer is free to produce what he thinks is needed, and each consumer is free to buy what he thinks he needs. Producers receive signals about what to produce from the buying habits of the consumers. The market is not always free; sometimes capitalists get government to creat a captive market, such as the California wine makers got government to place a 100% tariff on French wine, so that Americans have to buy the high-priced California wines instead of the lower-priced French wines. [They claim we are still free since we can still buy the French wine if we are willing to pay a lot more for it than the French wine-maker is asking for it. This is just a sophism (smoke and mirrors).]
Under the communist system, producers produce what ever a central, governmental planning board tells them to produce. The few people on a planning board can never know nor sift through all of the information that the free market produces and sifts for the capitalist producer. The communist consumers have to buy or reject whatever is put before them, because the producers are not responding to whether or not the consumers actually need their products; the producers are only responding to the central planning board, which cannot know and may not care what the consumers need. The planning board's decisions may be driven by factors such as a member of the governing body has a lot of rubber plantations and wants automobile tires made from natural rubber instead of better petroleum based rubber. (This kind of decision can be made under capitalism too.)
Guideance for the producer under capitalism comes from politically powerful individuals and from the market. Guideance for the producer under communism comes from the politically powerful and from communist party ideology.
Ideology is a political doctrine that promises salvation in the here and now if everybody will just do everything that the ideologist wants them to do, and if everybody does not want to do these things, then everybody must be forced to do them, or eliminated (starved, executed, worked to death). Ideology is really just the excuse of a power-hungry, and evil person or party of persons to sieze and hold all political power.
The principle of communism is to have everything, including production, serve the siezing and holding of power.