As stated in other resources youll find here on the site: Heathenry is broadly defined as "Germanic/Norse Neopaganism". It is the reconstructionalist faith that is based off pre-Christian religion and culture from Northern Europe. It is a polytheistic spiritual belief and as such there are many Gods, Goddesses and spirits (called Wights) associated with it.
As a whole, heathenry can be broken down into several different branches or sects depending on which deities or wights are honored, how it is practiced and what the practice encompasses, and who the specific people doing the honoring are. A joke I often hear, and find myself repeating, is that if you were to get ten heathens together in a room you would have ten different kinds of heathenry.
This is a very brief attempt to outline some of the different branches, and to define what they are. This is probably incredibly short and over-generalized, so if you find yourself interested in a specific branch I would highly encourage you to do your own research into it to learn more.
This is not all-inclusive. There are many more than listed here, though these are some of the larger or more well-known groupings. There are other groupings depending on which country you are looking at.
A concentration on Anglo-Saxon practices and beliefs. There are various branches within this grouping, including Fyrnsidu and Theodism. This may be a good resource to look into:https://ealdrice.org/
Asatru means true to the Aesir. Defining Asatru can be a bit tricky, as it can vary widely as a group. Asatru tends to focus mostly on Icelandic source material. Often, the Aesir deities (Odin, Thor, Tyr, etc) are the main focus of this group. Some who define themselves as Asatru may work with deities outside of the Aesir, however. Asatru within the USA is said to be very different in some cases from Asatru in Iceland or other Scandenavian countries. Within the USA, there seems to be little focus on nature (such as the landvaettir) as a whole and more focus on specific Gods and community (kindreds). See a more indepth discussion of Asatru here:http://www.spellsofmagic.com/read_post.html?post=386965
There are many variations of this branch within Scandinavia, according to geographical region. This branch is focused largely on folk belief and practices. It is less tolerant or accepting of new age beliefs and practices, and tends to focus on historical folklore and tradition. A lot of materials within this branch are in their traditional languages. Several different Scandenavian countries have official groups you can join, though some require that you live in that specific country.
This is a form of French Heathenry. As with some of the other country specific groupings, most of the literature and practice here is in their native language. It is suggested to have some similarities to Germanic Heathenry. A resource to look into:http://odroerirjournal.com/frankish-heathenry-an-introduction/
Heathenry in a general sense. Someone who considers themselves to be a general heathen might not want to be classified under any specific branch, may have interests in several of the branches and mix practices or deities that they work with. A very basic overview can be found here: http://www.spellsofmagic.com/read_post.html?post=511657
As with Frankish, this is a form of Germanic Heathenry. Most of the literature is in German. Many of the resources for this practice come from several different tribes. This thread contains resources you may look into:https://www.reddit.com/r/heathenry/comments/3429of/germanic_heathenry_resources/
Originally the term was coined by Abby Helasdottir, though the original version of Rokkatru did not line up with most of Heathenry in general. Rokkatru is also sometimes associated with Northern Tradition Paganism. Some who fall under this category would also fall under Asatru or General Heathenry, though they may focus on a deity that has been deemed one of the Rokkr (such as Loki and his kin, for example) or they may include work with the Jotnar (Giants). You can read more about it here: http://www.spellsofmagic.com/read_post.html?post=767428
Vanatru means True to the Vanir. This branch can be a lot like Asatru, though instead of a focus on the Aesir there is a focus on the Vanir deities. Which deities precisely get denoted as Vanir can vary from person to person though common ones known include Njord, Freyr and Freyja. This grouping tends to focus on nature, the landvaettir, the earth and fertility. Many of their sources may come from Swedish/Anglo-Saxon resources.http://coreyemmah.weebly.com/uploads/2/2/1/8/22181700/svartesol_-_vanatru.pdf
Lokeans are put down here simply because Lokeans, by themselves, tend to not be viewed as an individual sect. A Lokean can belong to any Heathen sect, or none of them. The only defining feature is that the person includes Loki in their practice. Read more about this grouping here:http://polytheist.com/orgrandr-lokean/2015/01/08/what-is-a-lokean/
Northern Tradition Paganism & Northern Tradition Shamanism
Both of these groupings were founded by Raven Kaldera and both state that they are not Heathen in origin. This practice relies a lot on UPG (Unverified Personal Gnosis) and PCPG (Peer-Collaborated Personal Gnosis). In some ways, this seems a lot like Norse Neo-Paganism to many. It borrows thoughts and concepts from many other practices and incorporates them into its own uses. You can read more about it here: http://www.spellsofmagic.com/read_post.html?post=538473
This is a branch of Wicca, or Neo-Wicca. This is not Heathenry.
Sometimes people think that Odinism means a specific focus on Odin as the main deity. Oftentimes, this is not the case. Odinism is often ritualistic or uses ceremonial magic and can be heavily racist as a group. Some people do not consider Odinists to be associated with the other branches of Heathenry hence its place here.
This group seems very much to resemble a neo-gnostic left hand path branch that takes issue with the majority of heathenry. Their main text that they rely on is Gullveigarbok by Vexior. You can read more about this specific grouping here:http://www.spellsofmagic.com/read_post.html?post=486564