There are two releases of EnTama. The EnTama (original release) has round beads on the strap. The beads on the EnTama CYOI strap are different - roughly square in shape. The top row on this page shows the three EnTama CYOI shell patterns:
https://tamagotch.channel.or.jp/toy/entama/lineup.html Note: the second row on that page shows the two Hanerutchi2 shell patterns. As you can see, they look physically the same as an EnTama. Internally, they're completely different. They're based on characters from a Japanese comedy troupe.
Anyway... back to the EnTama vs EnTama CYOI: Other than the beads, only the built-in games are different. Below is a quick guide how to play the EnTama CYOI built-in games.
Intelligence: The Turtle teacher is carrying stacks of books - in each hand and balanced on top of his head. Your goal is to keep him from dropping the books. When you see him start to sway to one side, nudge him upright. Press the A (left) button multiple times when he starts to sway to the right. Press the C (right button) multiple times to when he starts to sway to the left. If you nudge him in the wrong direction, or aren't fast enough, the books will topple over. This game lasts 30 rounds.
Style: The Gotchi King is wearing some fancy eyeglasses. He can make their pattern change. Unfortunately the pattern on one side keeps changing on its own. Press the B (middle) button when it's pattern matches that of the other side. This game lasts 6 rounds.
Kindness: The Flower Teacher has aphids! You've got to pick them off before they harm her. Aphids will appear as a small skull symbol on her petals. Move the petal selector counter-clockwise using the A (left) button, or clockwise using the C (right) button. When you've reached the affected petal, press the B (middle) button to pluck off the aphid. If you pluck off a petal that doesn't have an aphid on it, or you're not fast enough, you lose. This game lasts 100 rounds.
Note: if you decide to purchase an EnTama CYOI, take care to not confuse EnTama CYOI with the EnTama "CIAO" shell patterns.