lets say you are talking about the amount of numbers in the set of Integers. Which is infinity.
And then say, you take that same set, and remove all the odd numbers.
So. You have this: one set, and another set that is equal to half the first set, right? WRONG!
There are degrees of infinity. So, an infinite set can be more or less infinite than another set. Here is how you figgir it out.
What you must do is show that all the elements of a set can be mapped in a one-one function to all the elements of another set, and then you prove they have the same degree of infinity. If you can't do that mapping, then one is a lesser degree of infinity.
For example.
the set of integer:
{ . . . , -1, 0, 1, 2, 3, 4, 5, . . . }
The set of evens:
{ . . . , -2, 0, 2, 4, 6, 8, 10, . . . }
Sets say you multiplied ever number in the set of integers by 2. You get this: { . . . -1(2), 0(2), 1(2), 3(2), 4(2), 5(2), . . . }. Simplified, this is { . . . , -2, 0, 2, 4, 6, 8, 10, . . . }
basically, you have shown that for every number in the set of integers, there is a corresponding number in the set of evens, so the two are of the same degree of infinity. There is actually much more to this, but I ask you just to look at it and accept it in principal, because I don't want to type the rest. The same trick can be done with the set of odds if you, instead of multiplying everything by 2, multiply by 2 and then add or subtract 1.
However, no such operation can be performed with the Reals or the Rationals onto the Integers, so the degree of infinity that the reals have is greater than the degree of infinity represented by the integers, the whole numbers (which are also equivalent to the integers. I challenge those who have not done this to try and figure it out), the evens, the odds, etc.
So, I hope I answered your question.
but you can't add one to infinity, so I kinda just answered the unspoken question: "can one infinity be greater than another."