Profile 1.0
Profile 1.0 is the original hardware requirement for Blu-ray players and essentially meets the bare minimum for playing back Blu-ray Discs. You'll have no problem playing back a movie, listening to standard audio commentary, tracks or using interactive "pop-up" menus, but you won't be able to access advanced features like picture-in-picture video commentary or download any extra content online.
If you're the kind of person that never watches special features, you might be fine with a Profile 1.0 player, but be aware that you may not be able to take full advantage of more advanced Blu-ray features. Manufacturers aren't allowed to produce any more Profile 1.0 players, but it's not rare to see the older units still being sold--for example, the Sharp BD-HP20U is still widely available. With the price of Profile 1.1 players falling as quickly as they are, it's probably worth skipping Profile 1.0 players.
Profile 1.1 (also known as BonusView or Final Standard Profile)
Profile 1.1 allows for picture-in-picture commentary on certain Blu-ray Discs.
Profile 1.1 allows for picture-in-picture commentary on certain Blu-ray Discs.
There are several different hardware requirements (see the chart below), but it basically boils down to the addition of picture-in-picture functionality, also known as BonusView. Typically, Blu-ray movies use this feature to enable a small window of video commentary, where a director or actor talks about a scene while it happens in the background. Profile 1.1 players need to have the secondary video and audio decoders necessary to play a smaller video in the corner, while also playing the main high-definition movie in the background. Movie studios were somewhat reluctant to include BonusView functionality at first, but now many Blu-ray Discs include the feature.
Profile 2.0 (also known as BD-Live)
Profile 2.0 allows for Internet-enabled features, such as downloading movie trailers.
Profile 2.0 allows for Internet-enabled features, such as downloading movie trailers.
Despite Profile 1.1 also being known as Final Standard Profile, there's actually still another Blu-ray specification, Profile 2.0, also known as BD-Live. The reason it's called BD-Live is that the major difference between profiles 1.1 and 2.0 is that Profile 2.0 requires that the player have an Internet connection, usually via an Ethernet port. Although some Profile 1.1 Blu-ray players have an Ethernet port, these are strictly for firmware updates and can't be used to access downloadable content.
In addition to Ethernet connectivity, the other major requirement is 1GB of local storage capability. All that means is that the player has to have some way of adding storage to the player, which is where the downloadable content is stored.