transform - STFT multiplied with Gaussian window vs STFT multiplied by rectangular window

I am currently analysing my signal by looking at its spectrogram to determine the sinusoidal frequency content at the local sections of my signal overtime. I can do my spectrogram in 2 ways:

1. Directly get the FFT of each local sections. Same as I multiply each section by a rectangular window with a height 1 and get the FFT.


2. Multiply each section by a Gaussian window and get the FFT.

Apparently, I get 2 different pictures of my spectrogram. Number 2 is known as the Gabor Transform.

My question here is, what is the motivation for doing the Gabor Transform vs directly doing the FFT at each section of a signal?