A usual car engine has its cylinders lined up in two rows. And they are called inline engines. Every cylinder is attached to the crankshaft with its own attachment. The crankshaft is long and it is one of disadvantages of the inline engine. The crankshaft is long, and heavy, so it is harder to rotate it and gain RPMs.
The radial engine is constructed differently. Its cylinders are positioned around the crankshaft in a circle. They are placed just like the spokes on a wheel, and pointed away from the crankshaft. This way the crankshaft does not need to be long and heavy.