I walked them both. Beside of the above mentioned fact that the Podiensis is much more frequented they are different in character.
The Podiensis is physically more challenging, especially in the first ten days.
The Lemovicensis is smoother. Going through landscapes one could call “lovely”, interrupted by some bigger cities with historical charm (i.e. Bourges, Limoges, Perigeux). Topographically the hardest part is the name giving region of Limousin but it’s easy doable.
A good source of information is the website of the association of voie de Vezelay. It gives you good overview of the options, the accommodation possibilities and gps tracks of the way.
So, if you’re looking for social contacts a nearly perfect infrastructure for hikers and a perfectly marked route you should opt for the Podiensis.
If you prefer a more contemplative walk with seeing no fellow pilgrim over some days and expecting the unexpected in some occasions you should choose the Lemovicensis.
Just my 2 cents.
Ultreia