There's a lambda-calculus-like core to Lisps, but there's enough on top that I'm not comfortable saying that Lisp implementations are "just the lambda calculus." As for indentation-based syntax, there is a Scheme SRFI[^1] that specifies an indentation-based syntax, although I'm not sure how many Schemes actually ship with implementations.

[^1]: Various extensions to Scheme are proposed as numbered SRFIs; the extension in question is SRFI 49, as defined by http://srfi.schemers.org/srfi-49/srfi-49.html