Example:
Purchasing random laptop off the internet that runs other OS because it is cool and then trying to install Linux on it is not going yield good results unless you are willing to spend a lot of time researching and making sure you bought something that will work well, as well as spend some time fiddling around with drivers a bit and filing a couple bug reports. This would be because your using hardware that no Linux developer has direct access too. Essentially you are the primary means of support for that particular OS/Hardware combination.
Or you can purchase laptop from a company that provides support for your particular Linux/hardware configuration (ie: they sell Linux pre-installed) and then you will likely get close to a 'Apple-like' experience with it 'just working' out of the box.