Schema
Schema document is an XML document i.e., the structure of an XML document is specified by another XML document.
Schema supports variety of dataTypes similar to programming language.
In Schema, It is possible to inherit and create relationship among elements.
In Schema, It is possible to group elements and attributes so that they can be treated as single logical unit.
In Schemas, it is possible to specify an upper limit for the number of occurrences of an element
DTD
DTDs follow SGML syntax.
In DTD everything is treated as text.
This is not possible in DTD without invalidating existing documents.
Grouping of elements and attributes is not possible in DTD.
It is not possible to specify an upper limit of an element in DTDs