Those are not *wide variations* on how to be saved.
You presented two options.
One is by faith.
One is by baptism (works).
How the baptism is done is inconsequential.
You either trust Christ or you trust something else.
What the something else is doesn’t matter because NOTHING else can save. You’re just as lost trusting one religious activity as another.
Those are huge differences! If baptism is required for salvation and someone relies on the sinner’s prayer, or the people who advocate full mmersion are correct and others have only water poured over their heads, or those who say infant baptism does not suffice and one has only been baptized as an infant, then what happens to those who went the wrong way?