  In a multi-layer electronic system, stacking order provides a rarely-explored
degree of freedom for tuning its electronic properties. Here we demonstrate the
dramatically different transport properties in trilayer graphene (TLG) with
different stacking orders. At the Dirac point, ABA-stacked TLG remains metallic
while the ABC counterpart becomes insulating. The latter exhibits a gap-like
dI/dV characteristics at low temperature and thermally activated conduction at
higher temperatures, indicating an intrinsic gap ~6 meV. In magnetic fields, in
addition to an insulating state at filling factor {\nu}=0, ABC TLG exhibits
quantum Hall plateaus at {\nu}=-30, \pm 18, \pm 9, each of which splits into 3
branches at higher fields. Such splittings are signatures of the Lifshitz
transition induced by trigonal warping, found only in ABC TLG, and in
semi-quantitative agreement with theory. Our results underscore the rich
interaction-induced phenomena in trilayer graphene with different stacking
orders, and its potential towards electronic applications.
