Here's some pictures. Sorry if anything looks deceiving from the angles. The 19 is about a half an inch longer. The Shield is about a 1/4" shorter with the six round magazine and about a 1/4" taller than the 19 with the seven round magazine. I aligned them with the edge of a sheet of paper and marked the Glock with a black marker and the Shield with a red marker so it might be easier to see the difference.

Side by side shot of length difference.





A few shots of the height difference with both magazines.







The Shield is obviously thinner.



And here's the marked up paper in case my pictures don't do the difference justice.