There are many differences between a real op-amp and an ideal one. These differences are quite important for the correct development and operation of any circuit involving the devices.
A real op-amp (specifically the 741 model of op-amp chip) has the following properties:
The properties of an ideal op-amp are:
On a related note, my Electronics class at school was recently set the following question for homework:
Outline three important differences between an ideal op-amp and a real op-amp.
In answer to this question, a friend gave the following:
One of the differences between an ideal op-amp and a real op-amp is that an ideal op-amp is difficult to manufacture.
When marking this homework, my Electronics teacher simply burst out laughing at this, and promptly read it out to the class. Needless to say, very little work was done in the next few minutes while we laughed. And just in case folk were wondering, this was not stupidity on my friend's behalf. He put down the three correct answers, but in his usual style, this was simply added to the end.
Any of the ideal op-amp properties listed above would have been suitable answers to the question with the exception of the final entry on the list - the saturation levels of the op-amp are not normally considered an important aspect of the system.
The exam paper the question was taken from is the General Certificate of Education Advanced Level 12 June 1992 Electronics Paper 1 from the University Of Cambridge Local Examinations Syndicate - Oxford And Cambridge Schools Examination Board. The question is 9(ii)
The information on the properties of real and ideal op-amps is taken from my A Level Electronics course notes.