TON stands for Type of Number: it specifies whether the number is a full International Number (i.e. needs the + prefix), or a Country Code Number, or an alphanumeric sender (i.e. includes up to 11 characters of alphanumeric sender id, quite useful for branding/advertising).
NPI stands for Numbering Plan Indicator: it specifies which type of numbering standard the given mobile number is being followed. It could be the operator’s private numbering (for premium rated services for instance), or the E164 standard International mobile numbering.
Note: This also differ as per the SMPP Protocol version. You should refer based on the SMPP Specification.