Diff between Primary Index and Cluster Index in Axapta ?
The fields in the Primary key uniquely identify records in any given table. Each unique combination of Primary key fields uniquely identifies one (and only one) record in the table. Primary keys MUST be unique. There can only be ONE primary key per table. Not all unique indexes are primary keys.
The Clustered index is the physical order in which records are stored in the table. Say you have a clustered index on a text field called “Name”, and you insert a record with a name that starts with a letter D, the record will physically be inserted between the C and the E record. Clustered indexes do not have to be unique.
see this link.it has been already discussed.
Or, the post that Naresh copy/pasted that from: http://dynamicsuser.net/forums/p/37721/194382.aspx#194455