Power transformer:
It carrying high voltage..
It is delta connection TFR.
It is used to transmit the voltage from generating sation 
to distribution center.
Distribution transformer:
It carrying 440V 3phase star connection systm.
It is a home applaiance transformer.

Transformers are classified as two categories: power 
transformers and distribution transformers.
Power transformers are used in transmission network of 
higher voltages, deployed for step-up and step down 
transformer application (400 kV, 200 kV, 110 kV, 66 kV, 
33kV)
Distribution transformers are used for lower voltage 
distribution networks as a means to end user connectivity. 
(11kV, 6.6 kV, 3.3 kV, 440V, 230V)

power transformers are used in transmission network for
voltage ratings of(440kv,220kv,110kv,66Kv) and are generally
rated above 200MVA.

Distribution Transformers are used in (33 kv,11kv,6.6 Kv
)voltage levels in Distribution network and are generally
rated less than 200 MVA.

the main difference between power and distribution 
transformer is, distribution transf. is designed for max. 
efficiency at 60% to 70% load as normally doesnt operate at 
full load all the time. Its load depends on distribution 
demand. Where as power transf. is designed for max. effi. 
at 100% load as it always runs at 100% load being near to 
generating station.

power transformer generally operated at full load. Hence, 
it is designed such that copper losses are minimal. 
however, a distribution transformer is always online and 
operated at loads less than full load for most of time. 
Hence, it is designed such that core losses are minimal.

Both power and distribution transformers are used for T&D 
applications (transmission & distribution). The difference 
between power and distribution transformers refers to size 
& input voltage. Distribution transformers vary between 25 
kVA and 10 MVA, with input voltage between 1 and 36 kV. 
Power transformers are typically units from 5 to 500 MVA, 
with input voltage above 36 kV.

Powr transformer are used in transmission network to step 
up/down voltage viz 440/220KV, 220/110 KV,33/11 KV and 
generaly of capacity 1 MVA or more.
Distibution transformer as name implies are used in 
distribution network and steps down voltage to.433 KV & 
normally of capacity less than 1 MVA viz 11/.433 
KV,33/.433KV