2N2222A by Texas Instruments is a small signal NPN bipolar junction transistor (BJT) with a max collector-emitter voltage of 40V and a max collector current of 0.8A. It is commonly used for switching applications due to its fast turn on/off times (35ns/285ns) and high transition frequency (300MHz).
SMMBT3904LT1G by Onsemi is a NPN BJT with 3 terminals, 0.3W power dissipation, and 40V max collector-emitter voltage. Ideal for small outline applications requiring a transistor with hFE of at least 30, it operates up to 150°C and has a transition frequency of 300MHz.