Antenna as a receiver

Hello,

How does an antenna work as a receiver antenna ? How is it different from a transmitter antenna?

Depends on what you are talking about, the question is not specific; an antenna for bradcasting a single FM radio station for example, its lenght should be optimized for that carrier, whereas on the receiver side the antenna must be sized for a slightly broader band. Another point is that antennas designed for transmitters covering the surrounding region must be often sized to have a directivity gain pattern oriented to the more populated region, whereas the portable receiver would have a symetrical directivity gain pattern in all angles.

The other way to think of it is where the driving fore comes from.
With a receiving antenna, the radio waves (EMF) coming through the 'air' vibrate the electrons in the antenna which causes a current that can be amplified.
With a transmitting antenna, the transmitter causes a current to flow through the antenna that generates the radiated EMF. With a transmitting antenna, you generally want to get the transfer from the current in the antenna to the radiated EMF to be as efficient as possible which means you 'tune' the length of the antenna so as to set up a standing wave at the desired transmitting frequency.
As Andre says, a receiving antenna can therefore be just about anything as long as the EMF can move the electrons. However you generally want an antenna that will help the transfer of the EMF into the antenna current and, as with the transmitting antenna, you want to set up a standing wave (or as close to it as possible). That is why an AM antenna is generally quite long while an FM (or DAB) antenna is much shorter.
Antenna used for both transmitting and receiving (e.g. for CB or Amateur Radio work) mostly transmit and receive on the same frequency and so can be tuned for the transmission and have that work for the reception as well.
Susan

Antennas are reciprocal devices, thus a transmitter antenna can be used for receiver as well. https://en.wikipedia.org/wiki/Reciprocity_(electromagnetism)