I'm really confused about the differences between the products that ChessBase offers. For example, on the website, Deep Fritz is said to be an engine. But after a bit of research, it turned out that it holds a database, a multimedia directory, a playchess.com client, and a tactics trainer! ChessBase is only said to be a database although it also features training courses. Also, ChessBase markets Houdini which is said to be "the world's strongest engine". So, if it is, doesn't that make Deep Fritz rubbish ? Please clear my confusions.
Houdini is a chess engine written by an external developer. It is not a user interface that you can visually interact. This is where the confusion: when ChessBase mentions Houdini, they actually mean running the Houdini chess engine on their ChessBase user-interface. If you search on Wikipedia, Houdini is simply a chess engine and has nothing to do with ChessBase. ChessBase does that because they want to sell their user-interface bundled with a strong chess engine.
Similarly, Deep Fritz is a chess engine just like what Houdini is. Again, what they really mean is running the Deep Fritz chess engine on their ChessBase graphical user interface.
ChessBase = user-interface written by the ChessBase company Deep Fritz = the ChessBase user-interface bundled with the Deep-Fritz chess engine Houdini = the ChessBase user-interface bundled with the Houdini chess engine
Deep Fritz 14, Houdini 4, Komodo 9 and Rybka 4 all use the same Graphic User Interface (GUI). It allows you to blundercheck, do full game analysis, calculate elo ratings for sets of games. It has a Handicap and Fun mode for dumbing down these engines, so you have a chance. You can also play timed games, and adjust the engine's style. There is also a hotness meter that shows you how sharp or dynamic the position is.
ChessBase 13 cannot do timed games or full game analysis, but it can do infinite analysis. It can create opening and endgame theme keys, and has a search mask for locating games with certain traits quickly. Lists of games can be sorted by player name, year, result, elo rating, tournament just by clicking on the header.
Komodo 9 is probably stronger than Houdini 4 which is stronger than Rybka 4 which is stronger than Deep Fritz 14. Some people like the slightly weaker engines because they believe they have special characteristics, for example a sharp or solid style, more human feel, or the like.
Both ChessBase and the engine GUIs allow you to annotate games, add variations, draw arrows on the board, watch videos, do infinite analysis, play on Playchess. The Engine GUIs have some basic database functions. The Engine GUIs are mainly for playing against, and ChessBase is for building an opening repertoire, and preparing to play specific opponents.
Just adding a few details to Student T's answer:
Fritz denotes a chess engine as well as an (graphical user) interface. The reason for this is a historical one. Back in the times, almost all commercial chess engines would bring their own interfaces (Fritz, ChessAssistant, Shredder, Rebel, ...) - and a lot more stuff like databases. The hegemony of those commercial programs in the mass market was largely unbroken until maybe three or four years ago. After this, everything goes blurry and messy (Rybka, Stockfish, xfce, EGTBs, Online Chess, scidb, ...). But back to the point.
The distinction between engine and interface only emerged after the terms "Fritz" and "Shredder" were coined. There is a third term which is the database application. It can organise collections (databases) of games efficiently. To add to the confusion, ChessBase the company named their database product - you guessed it - ChessBase.
- If you buy Deep Fritz today, you get the engine and the interface and some extra stuff (but only a rudimentary database interface).
- If you buy ChessBase, you get the database interface (and probably databases and a player base), but no engines.
- All sorts of free strong UCI engines have emerged on the internet (some outperforming Fritz). You could use a free interface like Arena and a free engine like Stockfish and you probably wouldn't fare noticeably worse than with a $100 software bundle.