CEEDUMP is used by Language Environment for a formatted dump when an abend occurs. If the problem is related to an LE condition, this dump can be helpful in debugging the cause of the failure. If the problem is not related to LE, this dump may be misleading.
SYSDUMP is used by the system for dumping when an abend occurs that causes a system dump (hence the DD name). This dump can be very long but will usually identify the cause of the problem -- although it may require an expert in dump reading to identify the cause.