Regular No-Hole Card = Lose only original bet - Absolutely no HA difference to hole-card blackjack. Only slows the game down for the house. Player plays under the assumption that there is no dealer blackjack in either a Regular No-Hole Card or a Hole-Card case, but all hit/draw/stand/double/split plays are irrelevent if the dealer draws a blackjack after all hands are played on a Regular No-hole Card game. Unless you intend to hit/double a blackjack hand, in which case you jeapordize a possible push and win Vs a Hole-Card game where you jeapordise just a win, there is no difference.
When dealer's upcard is either an Ace (insurance is offered) or a 10, hole card is peeped. If no BJ, player will know that below Ace upcard is a 9 or less & below 10 upcard is not an Ace.
Player can then be more confident to split 8-8 or A-A or double down on 11 or 10.
... for instance, if the dealer checks twice under a ten, you can be pretty sure that the hole card is something that might look like an Ace at first glance: a 2 or 3 because of the way the pips are arranged, or a 4 because the upper part of the numeral looks like the upper part of an "A".
Blackjack table slide-in "hole checkers" only show an Ace or nothing at all under a ten-card. A non-ace card cannot look like an ace, because nothing is seen for a non-ace card when the cards are slid vertically into the peeker. This is because Ace cards have a "four corner" pip design that shows up in a peeker, and non-ace cards have only a two pip design.
For checking tens under an Ace (when calling for insurance), the ten card pips are place at a higher location on the card, so that tens will show the pip and the non-ten cards also show nothing.
There is no non-ace card that "looks like an ace" because all non-ace cards show nothing when checking under a ten.
There is also no pip showing when for non-ten cards when looking under an ace (sliding the cards in sideways for a Ten check).
This loophole was closed long ago with standard casino deck and peeker designs, because it was a give-away if the dealer were to check twice on a four card.