The TSOP38238 is an IR Receiver module for infrared remote control systems. In TSOP38238, a PIN diode and a preamplifier are assembled on a lead frame while the epoxy package acts as an IR filter.
The TSOP1838 is a miniature IR receiver IC form the TSOP18xx series. This particular model TSOP1838 will respond to 38kHz IR signals from remote control devices. It is normally used as IR receiver in remote control applications like TV, AC etc.