Don't worry, they all pressure cook, slow cook, cook rice, steam, keep warm, and saute.
More Info: Summary of the 3 main types of Instant Pot
There are essentially three main Instant Pot models. The LUX, the DUO, and the SMART.
We don't normally recommend the LUX unless you NEVER eat yogurt. Of the three, it is the only model that does not have a built in setting for yogurt. (However, there are workarounds.)
If you want to learn how to make your own Greek yogurt and cook at low pressure, the DUO is probably your best bet.
For the complete set-it-and-forget-it experience, complete setting control, a bigger display, and every available option, you will love teh SMART. Our only disclaimer is that you DO need to be a little bit "techie" to be comfortable with all the features.