  We investigate photometric properties of spiral arms and stellar
complexes/associations inside these arms in the grand design NGC 628 (M74)
galaxy.We analyze GALEX ultraviolet, optical UBVRI, and H-alpha? surface
photometry data, including those obtained with 1.5 m telescope at the Maidanak
Observatory. In the longer arm, the large and bright stellar complexes are
located at regular intervals along the arm, but only farther from the galaxy
center. They are joined with the narrow lane of dust, visible only in the
infrared bands. The usual dust lane along the stellar arm inner side is seen
there only at distances closer to the galaxy center. It is well expressed in CO
(H_2) image. We have found, that the second, short arm hosts two dust lanes,
the strong and wide at the inner side, and narrow and irregular along its outer
edge. This outer dust lane is well seen in IR images only. The shorter arm
contains no star complexes at all. Gradients of age and luminosity of stars
across both arms are missing (again excepting the parts of arms located closer
to the center), which is confirmed by our photometric cuts across both arms.
The drastic difference in the morphology of the two symmetric arms (grand
design type) of a galaxy has now been confirmed by objective measurements in
the case of M74. It is unclear why about two third of galaxies with beaded arms
host these "beads" (star complexes) in one arm only.
