I have 4 translations of the bible and am aware that translations differ. I also know that bibles can have different numbers of books, but?

There are standards

but...more than one standard, as you've noticed.

There's not a universal standard

for the same reason that there's not a universal standard on what books should be included

or even on the verse and chapter numbering (though Protestant verse and chapter numbering is NEARLY universal in the West now, except in Psalms).

Typically the Bible-savvy person can figure out these abbreviations without too much effort...

except in the cases of

Jude / Judges (requires three letters, usually Jde / Jdg)

Phillipians / Philemon (requires three letters, usually Php / Phm)

Ecclesiasticus (typically Sir or Si because an alternate title is ben Sirah)

I always use a three-letter abbreviation

for consistency's sake

but study Bibles and similar resources typically use a two-letter abbreviation whenever possible

probably to save ink and paper!

Use the original Greek text .

ONLY CATHOLIC BIBLES ARE DIFFERENT...CHOOSE KING JAMES OR REVISED...BOTH OF THEM ARE GOOD.

Could you name the bible translations you are referring to?

There are many christians who insist the King James bible of 1611 is the most accurate and reliable English version based on the Greek Textus receptus while modern bibles e.g ASV, NIV etc, come from a different Greek text commonly called the Westcott & Hort Greek text of 1881.

You may notice in modern bibles that they contain footnotes explaining why certain verses have been omitted or abbreviated because they are not available in the best or oldest Greek mss.

Yet the King James bible retains all those disputable verses.

e.g (Mark 16:15-20, Acts 8:37, & 1John 5:7)

btw- The Jehovahs witness bible NWT completely changes the meaning of (John 1:1) by calling the Word (Jesus) "a god" instead of "God" as all well known bibles render that verse as.

But its up to you to make your own mind up on what you believe to be the true and infallible word of God (bible)

The original and complete Bible has 73 books, which is what the Holy Spirit guided the bishops of the Catholic Church to include when they compiled the Bible in the mid-4'th Century. Every Bible on Earth included those same 73 books for the next 1,100 years, until one misguided Catholic priest thought He could do a better job of interpreting the Bible than the Church to which Jesus Christ had promised the fullness of God's truth. So Luther decided to trash 10 books of God's Holy Word - 3 New Testament books and 7 Old Testament books - whose teaching He didn't agree with. His own followers were near the point of rebellion over trashing the writings of the Apostles, so he had to back down on the 3 New Testament books, but still threw out the 7 Old Testament books. If he had his way, Protestants today would be using an incomplete bible of 63 books instead of the incomplete bible of 66 books they do use.

Because then all those True Christians™ couldn't feel smugly superior.

God works in mysterious ways and even when they are all different they can mean the same things Jesus said he is for you not against you child of God

My suggestion:  Get a Parallel Bible, which will have four translations side by side by side by side. The book, chapter, and verse will all be side by side. 

You can get it in a few different options:  

NIV, KJV, NASB, and Amplified

NIV, NKJV, NLT, and The Message

KJV, NKJV, NIV, and NLT

There is also an online version with 34 versions:  https://www.biblestudytools.com/compare-translatio...

You think that is a problem.

Why do the oldest complete Bibles - the Codex Sinaiticus and the Codex Vaticanus - have passages that are very different from any modern bible?

It's almost like it was made up, and then edited afterwards.