Why the sodium is nearly the same across salts
Table salt, sea salt, Himalayan pink salt, and kosher salt are all predominantly sodium chloride. By weight, their sodium content is very close, so swapping one for another does not meaningfully reduce sodium intake. The differences people notice come from crystal size, shape, trace minerals, and additives rather than from the sodium itself.
By volume, coarser salts like kosher and flaky sea salt pack less into a teaspoon than fine table salt, so a teaspoon of a coarse salt can deliver less sodium than a teaspoon of fine salt, which matters when measuring by spoon rather than by weight.
Trace minerals, additives, and texture
Sea salt and Himalayan salt contain small amounts of trace minerals that give colour and subtle flavour, but the quantities are too small to be a meaningful dietary source of those minerals. Standard table salt is often fortified with iodine, a deliberate public-health measure, and many specialty salts are not, which is a relevant distinction in regions where iodine intake is otherwise low.
This is general educational information, not medical advice. Anyone managing blood pressure or sodium intake should focus on total sodium consumed rather than salt type, and consult a qualified professional for personal targets.