I have three questions. One, can I install multiple versions of Python on my machine. I have a 4 Gb RAM system. Two, can I install multiple versions of Anaconda? Three, what is the difference between jupyter notebook & jupyter lab? Please help. I am a new user.
can I install multiple versions of Python on my machine?
Yes, and the conda package manager (which comes with the Anaconda distribution) will help with that. You can create a separate conda environment for each Python version you want to use by running:
conda create --name mypy36env python=3.6
conda activate mypy36env
For details on how to create and manage conda environments, take a look at the docs
can I install multiple versions of Anaconda?
You can but because of the answer above you don't need to and shouldn't. Instead of multiple Anaconda versions, just create multiple environments with the versions of packages you need.
You can create an environment with specific versions of Python and the Anaconda distribution with:
conda create -n anaconda201903 python=3.6 anaconda==2019.03
what is the difference between jupyter notebook & jupyter lab?
From the JupyterLab docs:
JupyterLab is the next-generation web-based user interface for Project Jupyter.
Basically JupyterLab is a new interface that allows you to create and run the same Jupyter notebooks you did in the past, but it also has much more functionality than the old interface.
For a bit more details, check this blog post.