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.

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.
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: The founding history & blockchain transaction history / 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