Lumped systems are those systems in which electrical
properties like R, L, C etc are assumed to be located on a
small space of the circuit. these systems are applicable
for low frequency application.
On the other hand Distributed systems assume that
electrical properties R, L, C etc are distributed across
the entire circuit. these systems are applicable to for high
(microwave)
frequency application.
Unlike the lumped element model, it assumes non-uniform
current along each branch and non-uniform voltage along
each node.