Online casinos are websites where you can gamble. You can place bets and play virtual games on the Internet. It's similar to regular land/bricks casinos. Online casinos are also named internet casinos, virtual casinos, web-based casinos etc.
Mobile casinos are casinos that you can play on your mobile phone. Sometimes you need do download the software, but mostly you can play in your browser, so called 'Instant Play'. The uses of mobile devices increases highly. Popular mobile devices are iPhone, Android smartphones, Blackberry, Nokia Windows Phones etc.
There are two ways of mobile playing:
1) Or players choose a mobile game 'app' to download to their phone;
2) Or he plays the mobile games in his phone built-in internet-/web browser. With this last option, the games don't hold up a valuable space in his phone memory.
You can play with almost every mobile device, such as iPhone, Android, Blackberry, Windows mobile, iPad, WAP, and even more...
When you are searching for a mobile casino, first look if you can register in that casino. Some online casinos are country specific. Almost every casino has restricted countries! So, it is possible that casino A is accessable to residents in US but not playable to players living in UK etc... The simplest way to find out is to registrate. You have to give up your mobile phone number. After having done this, the casino will immediately accept or not accept your phone number!
Mobile playing is NOT illegal. But gambling laws differ from one jurisdiction to another. Internet and/or mobile gambling is no different. As a player you have to encounter the legality issues of playing in your area. Each player is subject to the laws set forth in your jurisdiction.