You have a neutral bar. You don't have a ground bar. Your panels look exactly like mine, which feed all EMT metallic conduit, and the conduit is the ground path. Care for it kindly, fix gaps immediately.
Your main panel has a neutral bar which appears to be all-metal and by nature bonded to the panel box (which is ground), which is both allowed and required in a main panel.
Your sub-panel has a neutral bar which is insulated from the panel box aka ground, which is required in a sub-panel.
Beware, on an isolated neutral bar, there are often special screws, usually green, which screw through the neutral bar to bond it to the case (ground). You should take care that there are none of those on a sub-panel; on a main panel I would "belt and suspenders" that by also adding a bonding strap.