Differences between lexical features and orthographic features in NLP?

Question

Features are used for model training and testing. What are the differences between lexical features and orthographic features in Natural Language Processing? Examples preferred.

Answer 1

I am not aware of such a distinction, and most of the time when people talk about lexical features they talk about using the word itself, in contrast to only using other features, ie its part-of-speech.

Here is an example of a paper that means "whole word orthograph" when they say lexical features

One could venture that orthographic could mean something more abstract than the sequence of characters themselves, for example whether the sequence is capitalized / titlecased / camelcased / etc. But we already have the useful and clearly understood shape feature denomination for that.

As such, I would recommend distinguishing features like this:

lexical features: whole word, prefix/suffix (various lengths possible), stemmed word, lemmatized word

shape features: uppercase, titlecase, camelcase, lowercase

grammatical and syntactic features: POS, part of a noun-phrase, head of a verb phrase, complement of a prepositional phrase, etc...

This is not an exhaustive list of possible features and feature categories, but it might help you categorizing linguistic features in a clearer and more widely-accepted way.