anybody can differentiate sensor & transducer clearly with example? because many theories explain differently but there is always some confusions arise....

 

Well, that's life.
There are going to be different customary usages in different industries and with different measurements.
Sensor and Transducer are often going to mean one and the same thing; a complete assembly which is used to make some form of measurement.

For example, a temperature sensor or transducer is usually taken to mean the complete assembly of sensing element (resistance or thermocouple, for example) with a thermowell and a junction box in an enclosure.

However, if we consider an ultrasonic flowmeter, then it would not be usual to refer to it as a sensor but as a meter and here the term transducer would actually refer to the two or more ultrasound generators/sensors as distinct from the flow tube or amplifier.

You may find that some people will refer to a transducer when they are referring directly to the primary sensing element and sensor when they refer to a complete assembly.

A more meaningful distinction can be made when differentiating between transducer and transmitter.
The difference can be taken to differentiate between a sensor which transmits a raw signal to a remote signal processing and calculation unit e.g. a resistance temperature sensor which is connected as two three or four wire primary element to a remote display which will convert the measured resistance into temperature in the required units.

A transmitter is then a sensor which has on-node signal processing such that it transmits the processed data as a temperature signal. This might be 4-20Ma proportional to temperature (or any other analogue signal) or which will transmit data over RS 232/485 etc using MODBUS or some other protocol. In either case the remote electronics can be a very simple display or logger where no further signal conditioning (other than span and bias in the case of analogue signals) is required.

The problem is that not everyone uses the same distinctions nor is consistent in there use and you may either have to determine the implied meaning from the context or seek clarification