'If you do' vs 'then'

[drezzinator]

I have noticed that many cards use the phrase 'if you do' and some have 'then' and these appear on nearly the same types of cards/effects.

Electribonus - Discard a {L} Energy card from your hand. If you do, draw 3 cards.
(Rotom Plasma Storm #49)

Flare Bonus - Discard a {R} Energy card from your hand. Then, draw 3 cards.
(Numel Unleashed #35)

Flare Bonus - Discard a {R} Energy card from your hand. If you do, draw 2 cards.
(Torchic Primal Clash #26)

-Can I use Numel's Flare Bonus, not discard a card, and still draw 3 cards? (The 'if you do' effects imply that you have to discard to draw, but 'then' isnt as obvious)
-Why are these different? in particular the two Flare Bonus

 

[PokePop]

I can't say why they are different, but in all cases, if you don't do the first action, you don't get to do the second.