Is BCH just BTC with larger blocks? What else is different?

No, BCH & BTC - although they share a common ancestry from 31st October 2008 to August 1st 2017 - now differ on a wide variety of technical, economic, cultural & philosophical issues.

Larger blocksize was the precipitating factor that caused The Blocksize War, but even at that time the division was far more significant than the value of a single number in the Bitcoin codebase. The reasons the conflict was so intense was due to the widereaching implications & problems stemming from a small-block approach (at least in the eyes of the big-block - later BCH - community).

The misconception that BCH is simply BTC with larger blocks is a common piece of propaganda by the specific vendetta that many BTC advocates still hold for BCH advocates, along with naive repetition from observers not informed on the history & differences.

In the years since 2017, the BCH & BTC projects have continued to diverge at an ever-accelerating rate - technically, economically, culturally & philosophically. This process will only continue over time.

tip

The process of introducing this propaganda was thoroughly detailed in the book Hijacking Bitcoin, which is highly recommended reading.

Of course, that's simply one point of view. Unlike the small block BTC advocates, the BCH community has no fear of alternative narratives (readers can decide the truth for themselves) so it's also recommended to read Jonathan Bier's "The Blocksize War" and compare.

Differences

Among other things, BCH & BTC now differ on:

Blocksize: BCH has adopted an algorithmically adaptable blocksize while BTC has entrenched their certainty in a 1MB approach. This plays into the diverging plan for scaling, BCH has its plan for global scale while BTC has their plan.
Protocol upgrades: BCH does not have SegWit, Taproot or Ordinal Inscriptions like BTC. Likewise, BTC does not have CashTokens, the scripting upgrades required for AnyHedge & so on.
Governance & upgrade policy: BCH has the CHIP process, while BTC has a historical variety of methodology used for upgrades & often an explicit refusal to adopt a single known method for fear it may prove a centralised point of attack.
Ecosystem: Almost everything in the ecosystem surrounding the two currencies. Each side has their own technical tools, news & podcasts, discussion platforms, version of history, wallets, apps, conferences, meetups & so on.
Culture: Vibe, memes & general community approach, discussion & adoption strategies.
Whitepaper & Philosophy: The BCH community has retained a focus on the project vision, engineering roadmap & principles explained in the Bitcoin whitepaper. Because of this, the BCH community remains passionately steadfast they are the real Bitcoin. In contrast, BTC largely does not resemble the whitepaper any more, in its stated goals or its technical design. This has lead to BTC thought leaders seeking to minimise the importance of the whitepaper and original mission plus a confusing array of changeable & flawed replacement narratives.
Maximalism: Both sides are maximalist (or have maximalist elements), but they disagree about what Bitcoin maximalism means - both in theory & practice.
Hashrate: Hashrate differs, although this is subject to frequently changing market conditions.
Payments: BCH has retained the instant payments, low fees & transaction reliability of the original Bitcoin. BTC has decided to become a less-reliable, high-fee "digital gold" instead (due to a combination of technical & cultural reasons mentioned on the rest of this list).
Disinformation: BCH has (logically due to the history) a very different relationship to censorship & propaganda than the BTC community.
Layer 2s: BCH has not invested much time & effort into L2 solutions like The Lightning Network, although that's for a combination of pragmatic & ideological reasons (much of the BTC work can be copied if/when necessary).
Market performance: BCH has suffered in the initial run on the free market, although there is much to consider about that.

Similarities

It's actually more rare to find things BCH & BTC share these days than things they don't. Areas of overlap include:

Origins & distribution: Creation by Satoshi Nakamoto, the founding history & blockchain transactions / coin distribution up until August 1st 2017.
Bitcoin mining: The SHA256 mining algorith & thus ASICS & mining industry, although subject to the specifics of hashrate.
Branding: The branding & Bitcoin name, although this is often a charged issue due to dispute about the real Bitcoin.
Quantum Computing: Bitcoin's potential vulnerability to quantum computing. Note that this puts the BCH & BTC community on the same side with regards to finding a solution to this specific issue.

Differences​

Similarities​

Differences

Similarities