Adding to James Keuning's answer:
The way I think about lube and grease is that basically, grease is for things that don't get taken apart as much, and lube is for parts that get more care, more often, and are usually more easily accessible. This absolutely does not mean that bikes do not need grease or that it isn't as important as 'lube'.
I use lube on my chain, derailleurs, pivots, etc. This is usually done once a week depending on the weather (Chicago) when I clean and lube my drivetrain.
I use grease on the other parts that are usually only seen during a serious teardown, i.e. bottom bracket bearings, head tube bearings, wheel bearings, etc.
One place grease is of particular importance is in your shifters. Once or twice a season I like to remove the hoods from my shifters, blast everything out with degreaser, and then use a small brush to apply some heavy grease to the mechanical components. Places where I use grease more often are on my pedals and on my seat post.
If you get a jar or quality grease and a bottle of quality chain lube, you should be set for pretty much everything.