# Difference between two math signs

I've a question about two math different math signs:

What is the difference between $\approx$ and $\cong$?

• The first one means approximately equal and the second is the sign of isomorphism or congruence – Math1995 May 8 '16 at 12:09

$\approx$ means “is approximately equal to”. $\cong$ can have various meanings in different contexts, e.g. “is congruent to” in geometry, “is isomorphic to” in abstract algebra, “is homeomorphic to” in topology.
$\approx$ is used to show that two values are close to each other algebraically, for ex. $$\frac{1}{3} \approx 0.333$$ and $\cong$ is used to show that two geometric figures(like triangles) are "congruent", or you could also say equal(they have equal sides, angles, ...)