For questions about circuits that amplify the difference between two input signals but not the signal common to the two inputs (e.g. the long-tailed pair). Do not use for questions about operational amplifiers (which are a type of difference amplifier) unless the op amp is used as a differential amplifier -- use only the "operational-amplifier" tag for most questions about op amps (e.g. an op amp as an inverting amplifier).

For questions about circuits that amplify the difference between two input signals but not the signal common to the two inputs (e.g. the long-tailed pair or op amp differential amplifier). Do not use for questions about operational amplifiers (which are a type of differential amplifier) unless the op amp is used as a differential amplifier -- use only for most questions about op amps (e.g. an op amp as an inverting amplifier).