Data  DS1;
INPUT A $ B $ C $ ;
Cards ;
Small Tike Red
Med Bike Blue
Large Bike Red
;

Data DS2 ;
INPUT X $ Y $ Z $ ;
Cards ;
Small 10.99 1yr
Small 20.99 2yr
Large 50.00 1yr
;

run;

proc sql;
create table AllDS as
 select coalesce(ds1.a,ds2.x) as ax, b, c, y, z
  from ds1 full join ds2
  on ds1.a = ds2.x
  order by ax desc;
quit;

http://jaredprins.squarespace.com/blog/2008/5/3/merge-datasets-with-unlike-variable-names.html

Merge datasets with unlike variable names

SAS