Index number and Sequence number

Index number noun - A number or ratio (a value on a scale of measurement) derived from a series of observed facts; can reveal relative changes as a function of time.

Sequence number and index number are semantically related in ordinal number topic. In some cases you can use "Sequence number" instead a noun phrase "Index number", when it comes to topics like serial number, order number.

Index number and sequence number are semantically related in ordinal number topic. You can use "Index number" instead a noun "Sequence number", if it concerns topics such as serial number, order number.