Arduino UDP Receive block outputs the data received from the UDP local port as uint8 (single byte) values. The range is from 0 to 255.
From Android UDP Send block, you can send data as uint8, int8, uint16, int16, uint32, int32, single, and double.
Check whether you are sending the data as uint8 values from Android. If it is not, then the received numbers might differ.
Eg: Send the number '4' as uint32 from Android. The number will be sent as 4 bytes. You will receive four bytes in Arduino, as 0, 0, 0 and 4.