[exim] Different ACL Condition Combinations

I think one combine boolean conditions sevral ways. Are these all same?
Is there performance reasons or functional reason to choose which one---
or is it no different, only choose for readability?

warn condition = ${if <condition 1>}
      condition = ${if <condition 2>}
      <do something>

warn condition = ${if and {{<condition 1>}{<condition 2>}}}
      <do something>

warn condition = ${if <condition 1>{${if <condition 2>}}fail}
      <do someting>

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