Difference between differential line transceiver & differential line driver and receiver pairs
A differential driver generates a differential signal with complementary (+,-) sides.
A differential receiver receives a differential signal; that received signal is the difference between the + and - halves. For example, +0.25 - (-0.25V) = 0.5V differential signal.

A differential driver can convert a single-ended signal to differential, but it can equally merely buffer another differential signal. Differential signals are commonly generated and received on some inputs, outputs and IOs of large devices such as microprocessors.
Differential signals are used because they are more resistant to noise and capable of carrying high-bitrate signals more reliably.

A differential transceiver is a combination of the driver and receiver described above. In this case, the driver part can be disabled, so that it has no appreciable effect on the connected differential line. The transceiver then acts purely as a receiver. If the driver part is enabled, then the receiver continues to receive, but the internal logic behind it will often not be reading the signal at that time.

Most modern PCs contain a PCI Express (PCIe) bus that uses differential signalling. PCIe uses Dual Simplex signalling, so that signals generated by differential drivers are received by differential receivers.

By contrast, the bidirectional, differential DQS+/DQS- strobe signal in DDR3 memory, uses differential transceivers (actually pseudo-differential, but that does not matter in this discussion). The strobe can be transmitted either from memory to controller or from controller to memory, depending on which differential transceiver is switched on at any time.