system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does Charter think it is able to buy out TWC when Comcast couldn't? What changes can I expect?

Some changes I am concerned with (but there are many more)

Will TWC customers still be allowed to use their own Modem?
How will my internet quality be affected?
gpt
In terms of changes, no one has any idea what will happen.  The most common thing when 2 cable companies merge is that things keep going basically as before.  Then over a few years the services converge in terms of what is allowed and what is not. 

The reason it's may be allowed while TWC/Comcast was not was because of size.  TWC is the second largest cable company.  The second largest merging with the first largest makes a monolith that none can compete with.  However, Charter is NOT the largest cable company (they are 4th) and if Charter and TWC merged, Comcast would still be larger. 

To be precise, according to Wikipedia Comcast has 23 million subs, TWC 14 million and Charter 5.9 million.  So even combined they would only be at 20 million. wheres if Comcast and TWC merged they would have (23+14) 37 million while second place (Cox communications) has only 6 million.  

Most antitrust people see the 37 million vs 6 million as a problem for competition.  Wheres 23 million vs 20 million would actually be good for competition.