Do all parties in a Venture round get an equal stake for their money

When you hear about a "$10M Series X round lead by X" and see that it is a consortium of 5 different funds / investors do all the parties get an equal stake for their share. ie. if there where 5 parties they would each get 20% of the equity for sale.

Or does the leading party get a higher percentage for their money ?

The ownership % an investor receives is based on how much they invest and at what terms. I'd assume terms are similar for all VC firms, but the amounts invested are likely all over the place - some to avoid dilution from earlier rounds, some to increase ownership, some to get a seat on the board, etc.

It's based primarily on the deal terms.

Normally the fund leading the syndicate is the one putting in most and structuring the deal. Beyond the lead fund, syndicate members get equity based on their financial commitment

Also as TS said sometimes equity is diluted for certain perks, I.E. board seats, etc