For a layman, Is it possible to conclude that a person is having a cataract problem just by seeing eyes?

Does the white smear or spots on eyeball is any indication of a cataract

Just possibly, especially if one pupil is noticeably less black than the other in even lighting conditions, it can be suspected, but it's not a safe conclusion.

A cataract forms in the lens of the eye, BEHIND the iris.
Marks elsewhere are not cataract.

Many cataracts, however, are not easily visible without specialised lighting/equipment and differences in the pupillary appearance may not be down to cataract,.
though such a difference, especially if new, would require at least assessment.

UK optometrist

It is, but they need to go to an eye doctor for confirmation.