What are integers, signed/unsigned, real, floating point, BCD, etc. i understand what decimal, binary,oct and hex are.
You are dealing with two different concepts.
To review: storage of numbers is in individual bits gathered into groups called 'words'. While the individual bits can store useful ON/OFF information by themselves it is their use in these groups that numbers are stored.
The descriptions "integers, signed/unsigned, real, floating point, BCD" are different methods of using the bits to store the numbers. You describe three basic ways to use the bits.
Integers (whether signed or unsigned) begin with the least significant bit representing a 0 or 1 and each higher bit representing 2 times the preceding. The highest bit may or may not be used as a sign indicator.
BCD groups the bits 4 at a time. Each group can store 0-9. Each higher group's value is 10 times the lower group's value.
Real - Floating Point typically use the IEEE 754 method for storing much larger and smaller numbers. We won't go into the actual method here.
Your other descriptions - "decimal, binary, oct and hex" - are different ways of showing a stored value to YOU, the human. BCD has only one way of being shown practically and that is essentially the same as 'hex'. Real/Floating Point stored numbers could be shown as whole numbers (if that is what is being stored), with the use of decimal points or using exponential notation (7.2 E5 or 7.2*10^5 for example). The various methods are to make the value of a stored number useful to you.
So, the short answer is some of them are ways of storage, the others are methods of display.
As an addendum, another method of storage may be 8 bits at a time (or 16 bits - Unicode - if more complex alphabets are used) if text is being stored. It's display method, most practically is as characters of the alphabet or ideographs.
