Different parameters can define 5th Gen like Australian Military says that fifth-generation fighter aircraft are characterised by very low-observability including internal weapons bays, and vastly improved situational awareness through a network-centric combat environment.You missed the point of J-10 TVC demonstration actually.
However, does LO defines only 5th Gen ACs? The equipment on board and some other characteristics may come in handy by 4th generation planes for LO category or not?
Steps taken in reduction of RCS for LO are being applied in contemporary aircraft also such as RAM coating.
Treatments can be applied to existing designs to reduce RCS
o Apply surface coatings and edge treatments
o Reshape intakes and engine ducts
o Upgrade antennas and sensors
Situational awareness and network centric capability through radar/sensors/data link/avionics on aircraft and support from AEW platform is a major part of modern airforces and their aircrafts.
A major technical difference between 4/4.5 generation and 5 Generation would be internal weapon carriage.