When referring to a megabyte for disk storage, the hard drive manufacturers use the standard that a megabyte is 1,000,000 bytes. This means that when you buy a 250 Gigabyte Hard drive you will get a total of 250,000,000,000 bytes of available storage.
A food chain only follows just one path as animals find food. eg: A hawk eats a snake, which has eaten a frog, which has eaten a grasshopper, which has eaten grass. A food web shows the many different paths plants and animals are connected. eg: A hawk might also eat a mouse, a squirrel, a frog or some other animal.
A food web is just another layer of the entire process. A food chain is a simplified version of what really happens in nature. Very few animals just eat one food. A food web is nature's way of making sure that there is food to go around. Let's use the simple food chain we used earlier.