Correct way to change bytes in a file?

[Raptor88]

I'm a beginner working on my first Python program.  Using Python 3.6.

I don't understand what is actually stored in memory for the following two scenarios:

Scenario-1:

blist = b'\x76\x12\x0B\x08'
blist[2] = 10
TypeError: 'bytes' object does not support item assignment

After a LOT of Googling, I saw a post that suggested using the list() method.  So I tried scenario-2.

Scenario-2:

blist = list(b'\x76\x12\x0B\x08')
blist[2] = 10
No error

After more Googling I learned that scenario-1 is a bytes type and that is immutable.  Scenario-2 is a list type and lists are mutable which allows scenario-2 to work without errors.

In trying to understand this, what is actually stored in memory for the two scenarios?
After line-1 is executed in both scenarios, aren't the bytes in memory identical?

For example:
In scenario-1, I assume blist[2] = hex 0B = decimal 11 is stored in memory.
In scenario-2, I assume blist[2] is also hex 0B = decimal 11 stored in memory.

Am I wrong?  Please help me to understand this.