# ADI BOOK vs Theory 68

The clearest difference is ads: ADI BOOK at none against Theory 68's shown. ADI BOOK also leads on iOS requirement (13.0 vs 15.1). Theory 68's advantage is update cadence (every 4 days vs fortnightly). On price, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

ADI BOOK ships an update fortnightly, Theory 68 every 4 days. The most recent releases landed on October 5, 2026 and October 22, 2026 respectively.

## The numbers

| Metric | ADI BOOK | Theory 68 |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | **No** | Yes |
| Update frequency | Fortnightly | **Every 4 days** |
| Size | 61 MB | 153 MB |
| Requires iOS | **13.0** | 15.1 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 12+ | 12+ |
| Developer | [ADI BOOK LIMITED](https://appshunter.io/developer/1801016102) | [Mehmet Cagri Yalcinkaya](https://appshunter.io/developer/1844125903) |

## What reviewers say

### ADI BOOK

[App page](https://appshunter.io/ios/app/adi-book-instructor/id6743073433)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


### Theory 68

[App page](https://appshunter.io/ios/app/theory-68/id6806437618)

**In-app purchases:** none


## Frequently asked questions

### Is ADI BOOK free?

ADI BOOK is free to download, with no in-app purchases.

### Is Theory 68 free?

Theory 68 is free to download, with no in-app purchases.

### Do ADI BOOK or Theory 68 have ads?

Theory 68 shows ads; ADI BOOK does not.

### Which is updated more often, ADI BOOK or Theory 68?

ADI BOOK ships an update fortnightly, and Theory 68 every 4 days. Most recently, ADI BOOK was updated on October 5, 2026 and Theory 68 on October 22, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*