is and '==' i'm confused

[snippsat]

== when comparing values and is when comparing identities(which is object's memory address).
Can use id() to see this.

>>> a = "this is test string"
>>> b = "this is test string"
>>> id(a)
2777033042000
>>> id(b)
2777033041840
>>> a is b
False

>>> help(id)
Help on built-in function id in module builtins:

id(obj, /)
    Return the identity of an object.
    
    This is guaranteed to be unique among simultaneously existing objects.
    (CPython uses the object's memory address.)

So there is underlaying stuff going on eg -5 to 256 most used numbers has a optimization to cache these in same place in memory.

>>> c = 50
>>> d = 50
>>> c is d
True
>>> c = 257
>>> d = 257
>>> c is d
False