The first difference is that Glycerin 19 is softer than Ghost 14.
The second difference is Ghost 14 is more versatile than Glycerin 19 due to its firmer midsole. Ghost 14 could handle short runs while Glycerin is more suitable for long runs with relaxed paces.
Third, the Glycerin 19 comes in regular and wide versions whereas the Ghost 14 is available in narrow, regular, wide and extra-wide versions.