#### Answer

*Similarities: Spherical shape
*Differences:
- Number of peaks and nodes in the radial probability function
- The size of radial extension of electrons.

#### Work Step by Step

*Similarities:
- Both $1s$ and $2s$ orbitals have the spherical shape with the nucleus being its center. Both $1s$ and $2s$ orbitals are spherically symmetry and centered on the nucleus.
*Differences:
- For the radial probability function:
+) Peaks: Orbital $1s$ has 1 peak, while orbital $2s$ has 2 peaks. (The number of peaks is equal with the value of $n$)
+) Nodes: Orbital $1s$ doesn't have any nodes, while orbital $2s$ has 1 node. (The number of nodes is $n-1$)
- The radial extension of electrons in orbital $2s$ is greater than that in orbital $1s$, which means there is a higher chance of finding an electron further from the nucleus in orbital $2s$ than in orbital $1s$.