A good question, Aaron. A few points about the differences:
In the goblet squat, the kettlebell is a convenient, and light, counterbalance to allow you to squat deeply with perfect form. (We could discuss what constitutes perfect form but that wasn't your question.)
In the front squat, the purpose of the kettlebell is primarily as weight to make the squat more difficult. One of the errors we see in front squat form is people trying to separate the kettlebell from their body - this is incorrect in the kettlebell front squat.
In addition, the goblet squat keeps the weight in the center while the one-kettlebell front squat allows us to look for side-to-side differences.
I'm sure others will offer additional points but those are, IMHO, the main ones. The goblet squat is a teaching tool while the front squat is a movement or exercise that can be loaded with more weight, but let's not lose sight of the fact that, in the larger world of squatting, even the two-kettlebell front squat does not accept anywhere near the weight of a barbell front or back squat - the kettlebell front squat is still focused on perfect, deep squatting form and is not a competitive squat.
-S-
Steve Freides, StrongFirst Team Leader
http://www.kbnj.com
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