Subtle sensations in Vipassana and Zen
How can it be that two traditions have so radical approaches to our body ?


They have different teaching methods. Also, zazen is not usually presented with discrete steps (though there are some milestones), as opposed to the original "sati" meditations (anapanasati, satipatthana)


  Is it true that in Zen there are no stages where bodily sensations arise ?


I've never heard this said.


  If subtle vibrations arise while doing Zen, what is the right approach to them ? Ignore them ? Analyze them ?


The stock phrase in zazen is "you just sit".