One big difference to Forex are the big spreads. A spread is the difference between ask and bid prices. The ask price is the highest price that someone wants for a given cryptocurrency, this is essentially the buying price. The bid price is the lowest price someone is willing to give you for a given cryptocurrency, this is basically the selling price.
Cryptocurrencies are highly volatile, risky and complex products. Due to wide price fluctuations, trading them may result in significant loss over a short period of time. Leverage can work both to your advantage and disadvantage. As a result, trading cryptocurrencies may not be suitable for all investors, and you should never invest money that you cannot afford to lose.
Launched in 2015, Ethereum is a decentralized software platform that enables Smart Contracts and Distributed Applications (DApps) to be built and run without any downtime, fraud, control or interference from a third party. The applications on ethereum are run on its platform-specific cryptographic token, ether. Ether is like a vehicle for moving around on the ethereum platform, and is sought by mostly developers looking to develop and run applications inside ethereum, or now by investors looking to make purchases of other digital currencies using ether. During 2014, ethereum launched a pre-sale for ether which received an overwhelming response; this helped to usher in the age of the initial coin offering (ICO). According to ethereum, it can be used to “codify, decentralize, secure and trade just about anything.” Following the attack on the DAO in 2016, Ethereum was split into Ethereum (ETH) and Ethereum Classic (ETC). As of February 9, 2019, Ethereum (ETH) had a market cap of $12.49 billion and a per token value of $118.71.
There is also an Ethereum-based ETF pending regulatory review, and many such products are likely to follow. For now, there are just a few options available. For example, ticker symbol GBTC is one such security listed on the US-based OTC Markets Exchange, and is available at major online brokerages such as Fidelity, providing stock market investors a way to gain exposure to Bitcoin without buying the underlying or using a derivative.

On cryptocurrency mining: As noted, one way to invest in cryptocurrency is via cryptocurrency mining. That is a valid way to start investing if say you love computer gaming and need a new rig and want to invest in small amounts of cryptocurrency while maybe making back some of the cost of the rig (and maybe even breaking even) but that is an entirely different subject. The average investor will want to trade USD for cryptocurrency on an exchange and avoid the complexities and investments of mining. In all cases, unless you already have a good rig with a great graphics card, you’ll need to put down USD upfront anyway.
In 2018, the US Securities and Exchange Commission maintained that "if a platform offers trading of digital assets that are securities and operates as an "exchange," as defined by the federal securities laws, then the platform must register with the SEC as a national securities exchange or be exempt from registration".[22] The Commodity Futures Trading Commission now permits the trading of cryptocurrency derivatives publicly.[23]
The first decentralized cryptocurrency, bitcoin, was created in 2009 by pseudonymous developer Satoshi Nakamoto. It used SHA-256, a cryptographic hash function, as its proof-of-work scheme.[14][15] In April 2011, Namecoin was created as an attempt at forming a decentralized DNS, which would make internet censorship very difficult. Soon after, in October 2011, Litecoin was released. It was the first successful cryptocurrency to use scrypt as its hash function instead of SHA-256. Another notable cryptocurrency, Peercoin was the first to use a proof-of-work/proof-of-stake hybrid.[16]