The LCCN takes on different looks based on whether it is printed on the item or keyed into a new bib record. All forms indicate the same information.
For LCCNs assigned prior to 2001, the system prefers the machine readable form of an 8 digit number with zero's inserted in place of the hyphen to fill in for missing digits when fewer than eight are present: 73-33725 has seven digits so one zero is inserted in place of the hyphen:
010 [space][space]73033725.
Source: 73-33725
Keying into a bib record: [space][space]73033725
For LCCNs assigned after 2000, all four digits of the year being indicated in the LC number are included, so a 10 digit number with zero's inserted in place of the hyphen to fill in for missing digits when fewer than ten are present should be entered: 2001-87428 has nine digits so one zero is inserted in place of the hyphen:
010 [space][space]2001087428.
Source: 2001-87428
Keying into a bib record: [space][space]2001087428