character datatype explaination sought

I am testing Idempiere and have run across this in an example:

character(1) DEFAULT 'Y'::bpchar NOT NULL,

How does this differ from

character(1) DEFAULT 'Y' NOT NULL,



-- 
***          e-Mail is NOT a SECURE channel          ***
        Do NOT transmit sensitive data via e-Mail
   Unencrypted messages have no legal claim to privacy
 Do NOT open attachments nor follow links sent by e-Mail

James B. Byrne                mailto:ByrneJB@Harte-Lyne.ca
Harte & Lyne Limited          http://www.harte-lyne.ca
9 Brockley Drive              vox: +1 905 561 1241
Hamilton, Ontario             fax: +1 905 561 0757
Canada  L8E 3C3