Sql-server – Memory Usage of SQL Server

SQL Server instance on my server is using almost full memory available in my Physical Server.
Say if i am having 8GB of RAM than SQL Server is using 7.8 GB of RAM from system.
I also have read articles and also read many similar questions regarding same on this forum and i understand that memory is reserved and it is using memory.

But i have 2 same servers and 2 SQL Servers, why this is happening on a single SQL Instance not on other. Also when i run DBCC MemoryStatus than it is showing up…

VM Reserved 8282008
VM Committed 537936

so from this we know that SQL reserved whole 8GB memory, but why this VM Committed keeps increasing. What i understand is VM Committed is:

VM Committed: This value shows the overall amount of VAS that SQL Server has committed. VAS that is committed has been associated with physical memory.

So this is the memory SQL Server has committed (from this i understand that physical memory actually SQL Server is using at instance).

So like to know the reason behind this ever increasing VM Committed memory on my server and not on another.
Thanks in Advance.