SP estimation varies between teams

Story Points aren't developed, usable increments of value are. Why do management care about the numbers that are used?

As long as their estimation technique helps Developers get their arms around how much work they can take on, what more do management need to know?

Story Points are a means for Developers to estimate their work.  Once work begins, those estimates are no longer useful because new information is obtained that could potentially impact their initial estimate.  Story Points should not be used for anything beyond the Developers deciding if they think they can get that work done in a Sprint. 

As @Ian points out, no one should focus on how many Story Points are in a Sprint.  What matters is how much value is being created and delivered during the Sprint.  As Scrum Masters, you should educate "Management" about how the Developers are self-organizing and self-managing their work in order to deliver value that the stakeholders want. 

Going to leave this here for you to read as inspiration for the discussions with your fellow Scrum Masters and Management.

https://ronjeffries.com/articles/019-01ff/story-points/Index.html

Why does management want the teams to align on their method of estimation? What do they hope to accomplish or achieve? Chances are, there are better ways to do what they want than to align on the definition of a story point.

Thank you all for putting the time to answer, will share this with my colleagues :-)

I would not recommand aligned SP estimations. I know such requirements from management and my experience is that an relative estimation with computable values always leads to missunderstandings even if you try to explain it.

Maybe SP does not fit for your company. SP can help, but the Scrum Guide does not mention them.