  This article explores the differences between frame and coordinate
transformations in relativistic theories. We highlight the key role of tetrad
fields in connecting spacetime and frame indices. Using Maxwell's
electrodynamics as an example, we show that Maxwell's equations are invariant
under coordinate transformations but exhibit covariant behavior under frame
transformations. We also analyze the energy-momentum of an electromagnetic
field in different frames, providing deeper insights into the implications of
different frames of reference and coordinate systems.
