The tune of a tordion and that of a galliard are the same, and there is no difference between them, save that the tordion is danced close to the ground to a light, lively beat, and the galliard is danced higher off the ground to a slower, stronger beat.
Here are two different possible beat patterns for the tune Arbeau gives:
My hypothesis is that the strong beat is at the start in the tordion and in the middle (fourth kick) in the galliard. The effect in the tordion is to never finish phrases conclusively, with a delicious pause in the middle of the phrase as the dancers leap lightly through the air, like a run on sentence with commas rather than full stops.
A similar effect is possible with the 15th century Italian saltarello and piva steps, if you are a young metro like Cornazano.