If your target platform is Unix or Mac OS X, you must use a SQL Anywhere database.

If your target platform is BlackBerry, Embedded Linux, or iPhone, you must use an UltraLite database.

If the target platform is Windows 7, Windows Vista, Windows XP, or Linux, both SQL Anywhere and UltraLite are available. SQL Anywhere is often preferred because provides a fuller feature set and its additional memory requirements are rarely an issue.

If the target platform is Windows Mobile, such as on a Pocket PC or smartphone, you need to consider memory constraints, and possibly the tasks your application needs to perform. On Windows Mobile, SQL Anywhere requires approximately 6 MB of memory plus another 2 MB for the synchronization component, whereas UltraLite requires less than 1 MB and has synchronization built in. But, while UltraLite is considerably smaller, it does not offer the same support as SQL Anywhere for such things as complex queries, events, procedures, triggers, views, and so on.