Yes, both games have hexagonally-defined territory and players place cubes on spaces during the game, but they are not similar otherwise, primarily because Tobago is not a deduction game! In that game, players try to locate and be the first to reach buried treasures, but the treasures haven't been buried in particular spaces on the island, that is, they're not in fixed locations that players need to find. Instead, for each of the four treasures, over multiple turns players lay down cards from their hand that set conditions for where the treasure could or couldn't be: It's not on the beach, it's within two spaces of a statue, it's within one space of a jungle, etc. To put Tobago in real-life terms, you're not trying to find your car keys, which are definitely in one fixed space that you need to locate, but rather you're trying to navigate the town's zoning rules to determine where you can place that Arby's franchise you plan to open. No space on the game board is where X marks the spot until players say so.
Cryptid doesn't work like that. The beast that you're trying to locate has set up home in one specific space on the game board, and each player has a clue as to the beast's location. Clues — which I repeatedly call "rules" in my overview video because the clues function as rules for where you can search — set boundaries on where the creature can be: in a forest or swamp, within two spaces of an abandoned camp, within one space of animal territory, etc. These clues resemble the cards from Tobago, but they serve different purposes. If you combine all 3-5 clues Venn diagram-style, with the number of clues equalling the number of players, then exactly one space on the game board is valid for the cryptid's location.
Your job in the game is to find that space. To do that, on your turn you either question a particular player as to whether a space is valid according to their clue or you search in a space that you know to be valid based on your own clue, with players in clockwise order giving the thumb's up until someone gives a single thumb's down, at which point your search ends in failure.
As the designers note in their history of the game's development on BGG News, information is the game's only currency. Each time you search, you must reveal a possible location where the cryptid could be, placing one of your discs on that space. (If you've already placed a disc on that space due to someone else questioning you about it, you must then place a disc elsewhere. You're a bit of a blabbermouth, I suppose.)
Each time another player places a cube on the board, thereby indicating a space where the cryptid couldn't be according to that player's clue, you must place a cube on the board as well. Fair's fair — they revealed information about a dead space on the board, so now you must return the favor. You try to be as unhelpful as possible when doing so, but inevitably you will reveal something because placement in almost any space on the board reveals information about one or more possible clues that you might be following. Sometimes you're going to throw a guess out there via a search, and you'll win the game; sometimes you'll just end up revealing more information and possible giving the game to someone else. Them's the breaks.
The advanced game, which the designers call the "full game", doubles the number of possible clues from 24 to 48 because now inverse clues are allowed. Now you have to consider not only whether someone's clue relates to being within three spaces of a white/blue/green/black structure, but whether their clue relates to not being within spaces of such a structure.
I've played the advanced game only once out of five total games on a review copy from Osprey, and that game took far longer to play. You have to flip back and forth in your head between what's valid and what isn't, trying to view the negative (or positive) spaces of another player in total and comparing them against dozens of possibilities. Given that mental challenge, I expect Osprey Games' booth at SPIEL '18 to be a zone of silence, everyone staring at the board and concentrating. Shh, don't interrupt me — I'm thinking...