I've noticed a reception time difference between two TVs at home tuned
to different channels broadcasting the same live video/sound (e.g., a
presidential address before Congress with network-shared cameras). Both
home TVs used their own antennas.
The time difference may be due to how different networks
handle/transmit/ process the signal before it is ultimately send through
a communication chain to a local station's transmitter/antenna. Each
network communication chain probably involves different microwave,
satellite, or landline links, and assorted electronic equipment.