When looking through the SHT3 series from Sensirion AG, it’s not always clear what the 5th digit in the number means exactly (SHT30 vs SHT31 vs SHT35).
This was recently looked into by one of our technicians and he found that the part numbers with this difference are put through the same manufacturing process, but are later separated and binned during the testing process. They have different performance behavior with regards to accuracy and tolerance. For the full details see pages 2 and 3 of the following datasheet: SHT3x Specifications.