Type and xtype in SQL Server sysobjects

Type exists in 6.0, and xtype exists in 7.0:

Type
Object type. It can be one of the following values:
C = check Constraints
D = default value or default Constraint
F = foreign key constraint
Fn = scalar function
If = embedded table functions
K = primary key or unique constraint
L = Log
P = Stored Procedure
R = rule
Rf = copy and filter the Stored Procedure
S = system table
TF = table functions
Tr = trigger
U = User table
V = View
X = Extended Stored Procedure

xtype
object type. It can be one of the following object types:
C = check constraint
d = default value or default constraint
F = foreign key constraint
L = Log
fn = scalar function
if = embedded table function
P = Stored Procedure
PK = primary key constraint (type: K)
Rf = copy and filter the Stored Procedure
S = system table
TF = table function
TR = trigger
U = User table
uq = unique constraint (type is K)
V = view
X = Extended Stored Procedure