xs:date - an ISO 8601 date:

• A prefix of the minus sign ('-') mean "BC" (before common era).

• The common format is 'YYYY-MM-DD'.

• You can add a time to indicate the "start of the day"--which looks just like the dateTime

• A date instance is constrained just line xs:dateTime

xs:dateTime - an ISO 8601 date plus a time.

• The date is separated from the time by a 'T': 2005-03-10T02:00:00-08:00

• The time format is 'hh:mm:ss' with at optional fractional seconds and optional timezone offset.

• The timezone is Greenwich Mean Time unless you specify the offset.

• The constraining facets are: pattern, enumeration, whiteSpace, maxInclusive, maxExclusive, minInclusive, minExclusive