same table on different commands (inner join)
Command 1 is the SQL-89 standard for joining between tables.

Command 2 is the correct method of writing JOINs as per the ANSI-92 SQL standard (yes, that is 92 as in 1992). Some 23 years later and people still don't want to conform to ANSI-join standards.

Theoretically, there is no difference between the two in terms of performance, it's apparently just a hard habit for people to break and some find it more readable if they're used to writing queries in that way.

There's a few more reasons for why people use the old standard as opposed to the new one in this Stack Overflow post.

I also seemingly keep referring back to Aaron Bertrand's posts (even though this one is written about SQL Server). This one may give you some more information on why you should be using the ANSI-92 Standard style joins.