Language / Mushroom: pieczarka vs grzyb [24]

I learned that pieczarka was mushroom, but when it comes to food my family eats zupa grzybowa -- we don't say zupa pieczarkowa. Some internet searches turned up gryzb as being mushroom others as fungus. Is one word used more in some situations than other? Did I learn the wrong word in my studies or have we been using the wrong word at home (and eating fungus soup?). Any insight would be helpful.