Wedding Website for Split Ceremony & Reception

I think the best way to communicate this is via invite not website. If people are directed to a website with both they will absolutely think they’re invited to both. I would also be sure that the guests attending the reception only are aware the ceremony is happening elsewhere at a different time. A lot of people get offended by a reception-only invite especially if they think they’re going to see the couple get married. Regardless, I’d send out two sets of invites. One for ceremony + reception and one for reception only. If you really feel you need a website I’d recommend making two.

I agree, it would be better to send invitations

Yes I agree, it sounds like guests are in different "categories" depending on which event they are attending. Hopefully there are only a small number of people invited to the whole thing vs just the reception. Otherwise, feelings may be hurt when the reception folk realize that they are invited to just half of the event. These things need to be managed carefully to avoid making people feel like second tier.

I think probably you should avoid making the gap between "tiers" bigger. Doing two websites may come across like you're being exclusive between groups, which in a sense you are.