It seems that there are multiple different mental states that people have historically called "enlightenment", as well as many different types of contemplative practices with different underlying cognitive mechanisms. I link to and quote from a couple of papers showing this. Given the apparent multiplicity of "enlightenment" states and contemplative practices, I'd like to request that future discussions on these topics include more detailed references or descriptions as to which states and practices are being talking about.

Can enlightenment be traced to specific neural correlates, cognition, or behavior?

The term ’’enlightenment” is an extraordinarily imprecise construct. Using the term enlightenment or even the term more native to Buddhist traditions, “awakening” (bodhi), as if it referred to a single outcome either privileges one conception over others or else assumes that there is some commonality among the traditional goals of diverse contemplative traditions. There are deep disagreements over the nature of the goal between and even within various Buddhist schools. Scientific investigations cannot assume that there is any commonality among the transformative changes referred to as “kensho,” “stream entry,” “realizing the nature of mind,” and so on, that various Buddhist traditions take as various stages of awakening. Empirical investigations of these constructs can only proceed with reference to the specific psychological and behavioral outcomes described in the native discourse of a specific tradition (see Lutz et al., 2007). [...]

Given the differences between various competing conceptions of awakening, one scientific approach to tracing enlightenment would be to use the tools of social psychology to investigate which states and traits are valued in a particular community. For instance, recent work in moral psychology suggests how value judgments of people and practices as either enlightened or unenlightened could be traced to affective reactions of admiration and disgust (Rozin et al., 1999; Schnall et al., 2008; Brandt and Reyna, 2011; Schnall and Roper, 2011). Some of the most virulent disagreements over what counts as genuine awakening occur between closely related practice traditions, such as the debates between various Theravāda Buddhist traditions in Burma over which states are to count as realizations of nibbāna and which are instead to be counted (merely) as states of deep concentration. Surveying these debates, Sharf (1995) concludes “there is no public consensus as to the application of terms that supposedly refer to discreet experiential states within the vipassanā movement” (Sharf, 1995, p. 265).

Reconstructing and deconstructing the self: Cognitive mechanisms in meditation practice

While mindfulness (see Glossary), compassion, and other forms of meditation are increasingly being studied as interventions to alleviate suffering and promote well-being [3–10], it is not yet clear how different styles of meditation affect specific cognitive processes, nor how alterations in these processes might impact levels of well-being. Here, we address this question from the perspective of psychology and cognitive neuroscience to better understand how changes in well-being are mediated by alterations in distinct cognitive processes and in the structure and functioning of corresponding brain networks. [...]

In this article we expand our original framework to accommodate a broader range of traditional and contemporary meditation practices, grouping them into attentional, constructive, and deconstructive families. According to this model, the primary cognitive mechanisms in these three families are (1) attention regulation and meta-awareness, (2) perspective taking and reappraisal, and (3) self-inquiry, respectively. To illustrate the role of these processes in different forms of meditation, we discuss how experiential fusion, maladaptive self-schema, and cognitive reification are differentially targeted by these processes in the context of Buddhist meditation, integrating the perspectives of other contemplative, philosophical, and clinical perspectives when relevant.

Below is a table from this paper showing how it classifies various traditional and modern contemplative practices. (Click here to see a more readable version.)