As the game of bridge developed and later became a craze in the early part of the 20th Century, poker playing cards started to become differentiated from bridge cards. However, the difference between them had nothing do with the different games. Both games use an identical deck of cards. The difference was related to size and still is to this day. Poker cards typically measure 3.5 by 2.5 inches. Bridge playing cards are a quarter of an inch narrower, making them suitable for mixed teams that include men and women. That's the only difference and all major playing card companies use this nomenclature.
Ironically, many casinos in the United States use bridge size cards for Texas Hold'em. That's because they usually are a little easier to shuffle and deal, resulting in less fatigue for the dealers. These almost always have a standard, or small, index on the corners. They use poker size cards with a jumbo, or large, index for games like Blackjack. Interestingly, most home players prefer the wider poker size cards in a jumbo, or large, index. We don't know the reason for this, but perhaps it's just a little easier to see the cards on a long table. Whichever the reason, you should not assume that poker size cards are used for Texas Hold'em. Many experienced players prefer to play with bridge cards.
The biggest innovation since the introduction of the index and later the jumbo index has been the adoption of plastic as the material of choice for high end cards. Plastic poker cards by manufacturers such as Fournier last many times longer than their paper counterparts. They are much harder to produce, as the ink needs to be printed on special coatings that allow them to adhere to the cardstock. That is why it's important to use plastic playing cards on felt and similar materials, which help avoid scratching the coatings. But despite this limitation, plastic cards generally are more durable, flexible and easier to use.