An ion has a positive or negative charge. While a covalent bond always has no charge, meaning it is neutral.
Explanation:
Method of prepration of sodium thiosulphate - definition
In the laboratory, this salt can be prepared by heating an aqueous solution of sodium sulphite with sulphur or by boiling aqueous NaOH and sulfur according to this equation:

Answer:
they are similar becauze they measure temperature