A swarm of bees.  Docile, fast, easy.

A hive of bees.  Aggressive, time-consuming, difficult.

The two pictures above illustrate the difference between a swarm of bees and a hive of bees.  If you've got bees living in your wall, tractor tyre, or in a tree-trunk, then it's a hive.  If there are a bunch of bees hanging out in the open, off a branch, on a fence-post, or in some shrubs, then it's a swarm.

The different is actually really important!  I get a lot of calls from people asking if I can quickly remove a swarm of bees.  When pressed, they say the bees have been there for several months/years - which means it's a hive of bees, not a swarm.  A swarm of bees requires driving to the location, suiting up a little, and maybe 5-15 minutes of work.  I'm unlikely to get stung.  Removing a hive of bees requires me to drive to the location, suit up completely, bring a lot of extra equipment, and then painstakingly remove empty comb, live bees, baby-bees, and honeycomb from a cavity of some kind (often requiring dismantling of the surrounding structure), while the entire hive tries to sting me.  I always get stung (the suit is more of a deterrent than armour), sometimes a lot - and the process takes hours.

You can imagine why I charge a minimal fee (sometimes free) for the first, while I charge an hourly rate for the second!