Kegs, beer bottles, growlers and wine bottles all mark an important closure to the initial phases of the brewing process. From here the steps are just as crucial, however they come with their own challenges and equipment.
There are many factors in determining the path for you. For example, the price of bottling compared to kegging can be much lower. You can recycle bottles, and simply purchase a capper and some caps. This method generally involves using some priming sugar to build the pressure and the bubbles in the bottle after it has been capped. Although priming sugar is not necessary if you are going from something already pressurized...such as a keg! The reason you may be choosing both kegs and bottles is for storage reasons, or maybe even for gifting.
One more important factor to consider with bottles is the color of the bottles. Light is beers enemy. That is why any beer that might have a shelf life is bottled in green or brown bottles. Clear bottles will not keep out the light, and therefor are a poor choice
Kegs on the other hand certainly require less steps, however it requires some more capital as far as expenses go. CO2 tanks are used to pressurize (note you can also use priming sugar for carbonation), and you have the investment in the kegs. Cornelius kegs are a common method, and very easy to store and transport. You can get very inexpensive tap systems as well. These types of kegs are not the only ones available. The only requirement besides being able to stay clean is that you can seal it with pressure. 15.5 Gallon kegs can easily be converted with some welding experience.
These are not all of the considerations but lay some of the groundwork. Its very possible that you end up with both bottles and kegs in your beer room, refrigerator or kegerator.