Why there are two prices
Telegram Stars (currency code XTR) are bought by users inside Telegram, through app stores or Fragment, and spent on digital goods in bots and Mini Apps. Users pay a retail price that includes store fees, so buying a Star costs more than an owner later receives for it.
Owners who collect Stars can convert them to Toncoin through Fragment after Telegram's holding period, or spend them on Telegram Ads. The withdrawal value is therefore the useful number for estimating income; the buy price is the useful number for pricing a product.
Exchange rates move. Use this converter for planning and always confirm the final amount in Telegram or on Fragment before you make a decision.