Flask is an open-source lightweight web framework built in Python to deploy web applications. To begin using Flask, we must first install it on our local machine
Streamlit is an alternative to Flask. The most significant benefit of using Streamlit is the ability to include HTML code inside the framework Python file. It does not involve different templates and CSS formatting for the front-end UI.
Flask very conveniently scales, can be customized to your liking and is thoroughly tested. Additionally, there is a lot of support within the community. On the downside, it can be overwhelming to begin with and the user needs to have knowledge about frontend development as Flask only provides backend support.
On the other hand for Streamlit, there is no reason to be concerned with front-end development, it is easier to grasp and takes less time between the development and deployment stage. But it has its own drawbacks, there is no scaling, it is not yet fully developed and lacks many features of Flask as it is in beta. Additionally, it does not have the vast community and support ecosystem enjoyed by Flask.
For relatively simple apps Streamlit would suffice. But if the user requires a more secure full-fledged app then Flask would be the better option.
We already discussed the general case but we can always pack the application into a container and further implement it with an orchestration platform. What this does is, adds additional layers to the pre-existing structure defined above.