Are there any differences between a Lorentz scalar quantity or a Lorentz invariant quantity? That sound be stupid but we dindt find anything exaustive about that. Take as example the power irradiate by an accelerated charge (Larmor formula, relativistic one). The expression for evaluating in two frames (rest and lab) are different but they refer to same value (if 10W is in one frame, 10 W is in the other). Is it a scalar or an invariant? We really appreciate your help, Ll.