There is a distinct and specific difference in size for the 1960 and
1960-D cent dates. The large date has the loop of the 9 sticking up well
above a line drawn across the tops of the 1 and 0. The small date has the
top of the 9 level with the 1 and 0.
There is no visible difference in size between the so called "large" and
"small" date 1970 cents. The large date has the top of the 7 below the
tops of the 19 0. The small date has it even with the other digits. The
quickest and simplest way to tell the two types apart is to check the tip
of the loop of the 9. If it is bent sharply toward the stem, then it's the
"small" date, or type of 1971.
The Z stands for the zinc core cents struck beginning in 1982, which are
20 percent lighter than the previous (C) cewnts. The C stands for copper,
but they are actually brass, 95 percent copper and 5 percent zinc.