The main difference is:
full version can display phpbBB wrapped into Joomla template with custom SEF URLs, specially adopted phpBB style is required. Certain Joomla extensions and phpBB MODs can conflict. Joomla template and phpBB style can have CSS conflicts.

lite version displays phpBB as it is ...

Each menu item can use own template style in Joomla, SEO is configured in menu items.
MightySites is not related to any GEO.

... term setting "Custom Tip Title" to display custom title in term tip.
⋅ Feature: global "Term List" default settings in component options.
⋅ Feature: new term list setting "Term Style" allows to configure preferred output of a term, i.e. with a tooltip.


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⋅ Change: row repeatable backgrounds moved to "Table Style".
⋅ Feature: "Repeatable Backgrounds" for columns (we already had the same feature but for rows).
⋅ Feature: new frontend/backend advanced settings "Preserve Pagination" and "Preserve Ordering" control the ...

... current behavior. Row Number column displays row numbers, you can disable "Row Numbers" option, add "Row Number" column and apply custom position/style easily. More column types are coming...
⋅ Feature: display global component setting value if a report setting is inherited.


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... sdot; Feature: 'Allowed/Disallowed K2 Categories' setting to protect K2 content.
⋅ Feature: new override setting 'Homepage Template Style' to always set custom homepage template style.
⋅ Feature: direct share of native Joomla custom fields (including categories and groups ...

Use native or our style and customize them via custom .css file only.

Hi, what's the best way you suggest to apply styles customizations and mantain them through phpbb updates?

I don't think that this will work, each style has different templates and different theme.

Sorry I meant using your style and only change the theme