50 pence 1969.
50 pence 1982 (proof FDC version).
There were also considerable differences between the older and newer versions of the Britannia design on the reverse of the fifty pence.
1] On the older version, the trident appears closer to the rim. Its middle prong is shorter and the tow other prongs are less broad at the tip.
2] On the newer version, Britannia is holding the trident at a lower angle. This is presumably to avoid overlapping the letter "T" in the word "FIFTY".
3] On the newer version, the crest of Britannia's helmet is wider than before, and the top right-most point of the crest extends further.
4] On the older version, the bottom-most point of Britannia's helmet has a small upward curl to it. This has disappeared on the newer version.
5] On the newer version, Britannia's profile looks somewhat different and seems to be broader than before.
6] On the newer version, Britannia appears to have less hair falling onto her neck.
7] On the older version, Britannia appears to facing more to the front than on the previous version. This has the effect of making the outline of her breasts look more pronounced than on the newer version. More of her stomach is visible, as it is turned more towards us, and you can see more of how the folds of her dress fall.
8] Britannia is sitting in an apparently more "comfortable" position on the newer version, so that her thighs and knees are held higher up.
9] On the newer version, Britannia appears to have fewer folds in her dress, yet the folds at the bottom left, close to the shield, look more complex than in the older version.
10] On the older version, the two main crosses on the representation of the Union Flag on Britannia's shield run together; on the newer version, they are clearly separated by a dividing line.
11] On the newer version, the sprig Britannia is holding appears to have broader leaves. And look at the right-hand side of the sprig on the older version: there are three leaves growing together in a cluster; this threesome has disappeared on the newer version.
12] The fur on the lion's front appears to extend further to the right on the older version. And on the newer version, there is now a gap between the bottom part of the lion's front fur and its feet - though I am not sure whether they are meant to be the lion's feet or whether it is the bottom of Britannia's robe piled up on the floor.
13] On the older version, the numeral zero in the figure fifty seems to be narrower than in the newer version.
These are all the major differences I can see. There do seem to be some other minor differences, but these may simply be down to the different amounts of wear on the coins in the images.