While English does not have a conditional tense per se as do the Romance langugages, including French from which English is derived (among other languages), there are certain words that used to establish a conditional situation.
In informal English, speakers and writers use the word if to begin clauses that are conditional. e.g. If this be true, we will not delay. Along with the conjunction if, the subjunctive mood is used for the predicate [be is in subjunctive mood]. (This is why speakers say If I were you instead of if I was you)
Should is a verb that is employed as a conjunction like if in this conditional tense, although it is not used as frequently as if, especially in America. This avoidance of its usage may be to avoid confusion since should is used used as an auxiliary verb to express necessity or obligation. Here are examples that illustrate the difference between should as a conjunction (1), expressing a condition and should as an auxiliary verb in a sentence expressing necessity (2):
- Should you move out, I will not be able to pay the rent on this apartment.
- I think you should move out of this apartment.
Therefore, the short answer to your question of whether should can have the same meaning as if is yes, sometimes.
So are you asking whether the word "should" means the same thing as "if?" If that is what you are asking, the answer is no -- they do not usually mean the same thing.
The word "if" is a conditional word -- it says that in a given circumstance something will happen. So you say "If you give me money, I will give you a car." So you get the car as long as you give the money.
It is possible for should and if to mean the same thing. You can use the word "should" just in the same way I used "if" above. You can say "Should you give me money,..." But this usage is very unusual in American English.
More often in American English, the word "should" tells what a person ought to do, what is right for them to do. So you can say "A person should not steal from another person." That word has a moral value to it -- it says what thing is supposed to happen.