Rangkaian Jembatan Penyearah Sepenuhnya-Terkendali ALL IZ WELL - Fina UNEJ

I wanted to figure out the relationship between an SCR and a Triac. It looks like the Triac will conduct in either direction and will turn on with a negative voltage on the gate while the SCR behaves more like a diode with a switch: it will only conduct in one direction and requires very little voltage to turn on.