The differences between different SPICE PACKAGES for computer aided circuit analysis are in the circuit description for the solver that is the circuit entry. But most of the SPICE alternatives uses graphical entry of the circuit elements and components
The core of the spice program which is the mathematical solver is the more or less the same. After getting the solution, one has to evaluate it by post processing tool. This tool varied from one package to the other. The final difference is in the components in the library. That is the model library. The more complete the better. So, it is said that LT SPICE FROM LINEAR TECHNOLOGY CONTAINS THE LIBRARY OF THE POWER SUPPLY CIRCUITS PRODUCED BY THEM.
Then i you use LT devices then it is simpler to use LTSPICE.