In obsolete|lang=en terms the difference between teston and testor
is that
teston is (obsolete) a tester; a sixpence while
testor is (obsolete) a teston, a sixpence.
As nouns the difference between teston and testor
is that
teston is (obsolete) a tester; a sixpence while
testor is (obsolete) a teston, a sixpence.